Appendix A — Explanatory Notes to Part 9

The NLGA “Standard Grading Rules for Canadian Lumber” permit lumber to be dressed to sizes below the standard sizes (38 x 89 mm (2" x 4"), 38 x 140 mm (2" x 6"), 38 x 184 mm (2" x 8"), etc.) provided the grade stamp shows the reduced size. This Sentence permits the use of the span tables for such lumber, provided the size indicated on the stamp is not less than 95% of the corresponding standard size. Allowable spans in the tables must be reduced a full 5% even if the undersize is less than the 5% permitted. Appendix A • Volume 2 Page 177 A.9.3.2.9.(1) Clearances Under Structural Wood Elements for Inspection. Figure A-9.3.2.9.(1) illustrates clearances under structural wood elements and visibility of supporting elements where required to permit inspection for termite infestation. Figure A-9.3.2.9.(1) Clearances Under Structural Wood Elements and Visibility of Supporting Elements Where Required to Permit Inspection for Termite Infestation A.9.3.2.9.(3) Protection of Structural Wood Elements from Moisture and Decay. There are many above-ground, structural wood systems where precipitation is readily trapped or drying is slow, creating conditions conducive to decay. Some examples of elements that can accumulate water when exposed to precipitation if they are not detailed to allow drainage are: • beams extending beyond roof decks • junctions between deck members • connections between balcony guards and walls.

Retaining walls supporting soil are considered to be structural elements of the building if a line drawn from the outer edge of the footing to the bottom of the exposed face of the retaining wall is greater than 45° to the horizontal. Retaining walls supporting soil may be structural elements of the building if the line described above has a lower slope. Figure A-9.3.2.9.(4) Identifying Retaining Walls that Require Preservative Treatment Retaining walls that are not critical to the support of building foundations but are greater than 1.2 m in height may pose a danger of sudden collapse to persons adjacent to the wall if the wood is not adequately protected from decay. The height of the retaining wall or cribbing is measured as the vertical difference between the ground levels on each side of the wall. Page 178 Appendix A • Volume 2

Article 9.4.1.l. establishes the principle that the structural members of Part 9 buildings must • comply with the prescriptive requirements provided in Part 9, • be designed in accordance with accepted good practice, or • be designed in accordance with Part 4 using the loads and limits on deflection and vibration specified in Part 9 or Part 4. Usually a combination of approaches is used. For example, even if the snow load calculation on a wood roof truss is based on Subsections 9.4.2., the joints must be designed in accordance with Part 4. Wall framing may comply with the prescriptive requirements in Subsections 9.23.3., 9.23.10., 9.23.11. and 9.23.12., while the floor framing may be engineered. Design according to Part 4 or accepted good engineering practice, such as that described in the “Engineering Guide for Wood Frame Construction” (2014 CWC Guide), published by the Canadian Wood Council, requires engineering expertise. The CWC Guide contains alternative solutions and provides information on the applicability of the Part 9 prescriptive structural requirements to further assist designers and building officials to identify the appropriate design approach. The need for professional involvement in the structural design of a building, whether to Part 4 or Part 9 requirements or accepted good practice, is defined by provincial legislation and is reflected in Section 1.2. of Division C.

The only explicit treatment of structural loads in Section 9.4. is for gravity loads; wind and earthquake loads are dealt with implicitly in the body of Part 9 and are not used as inputs to any of the span tables. There may therefore be a tendency to assume that wind and earthquake loads do not need to be considered in the design of Part 9 buildings. In most cases this is true: the majority of low rise, wood frame buildings have a great deal of structural redundancy and continuity and have more than enough capacity to resist lateral loads due to wind and earthquake. For example, in a traditional house configuration, even if there are large openings in the exterior walls for picture windows and sliding doors, the many interior partitions act as shear walls and provide adequate lateral stability. This may not be the case for some newer house designs. However, this does not apply to all building configurations or details that might be found in Part 9 buildings. For example, a mercantile building might be long and narrow with almost entirely windowed walls on the ends and few structurally attached interior partitions. See Figure A-9.4.1.1.(3)-A. In such a case, wind and earthquake loads would have to be considered in the design of the long structural walls and their foundations. Figure A-9.4.1.1.(3)-A Mercantile Building with Little Resistance to Lateral Loading Appendix A • Volume 2 Page 179 Many buildings have been constructed with the lowest level exterior walls as short, wood-frame knee- or pony-walls. In the past, these were often constructed with no lateral bracing and with no interior partitions. The only structural continuity in the foundation-to-knee-wall and knee-wall- to-floor joints comes from nailing and this is inadequate to resist lateral loads from significant earthquakes. See Figure A-9.4.1.1.(3)-B. These walls must be braced or sheathed to resist lateral loads from earthquakes. In higher load regions, they should be sheathed. In all regions, storeys with knee-walls should be considered as storeys for the purpose of determining building height and the application of the Part 9 structural requirements. Figure A-9.4.1.1.(3)-B Crawl Space Knee-wall with Little Resistance to Lateral Loading Thus, Part 9 buildings are not exempt from having to comply with the wind and earthquake loading requirements of Part 4. In many cases, these considerations can safely be ignored but, in certain configurations, the building’s resistance to wind and earthquake loads must be carefully considered. See also A-9.23.10.2. In cases where lateral load design is required, the “Engineering Guide for Wood Frame Construction” (CWC Guide) provides acceptable engineering solutions as an alternative to Part 4. The CWC Guide also contains alternative solutions and provides information on the applicability of the Part 9 prescriptive structural requirements to further assist designers and building officials to identify the appropriate design approach.

The simplified specified snow loads described in Article 9.4.2.2. may be used where the structure is of the configuration that is typical of traditional wood-frame residential construction and its performance. This places limits on the spacing of joists, rafters and trusses, the spans of these members and supporting members, deflection under load, overall dimensions of the roof and the configuration of the roof. It assumes considerable redundancy in the structure. Because very large buildings may be constructed under Part 9 by constructing firewalls to break up the building area, it is possible to have Part 9 buildings with very large roofs. The simplified specified snow loads may not be used when the total roof area of the overall structure exceeds 4 550 m2. Thus, the simplified specified snow load calculation may be used for typical townhouse construction but would not be appropriate for much larger commercial or industrial buildings, for example. The simplified specified snow loads are also not designed to take into account roof configurations that seriously exacerbate snow accumulation. This does not pertain to typical projections above a sloped roof, such as dormers, nor does it pertain to buildings with higher and lower roofs. Although two-level roofs generally lead to drift loading, smaller light-frame buildings constructed according to Part 9 have not failed under these loads. Consequently, the simplified calculation may be used in these cases. Rather, this limitation on application of the simplified calculation pertains to roofs with high parapets or significant other projections above the roof, such as elevator penthouses, mechanical rooms or larger equipment that would effectively collect snow and preclude its blowing off the roof. The reference to Article 9.4.3.1. invokes, for roof assemblies other than common lumber trusses, the same performance criteria for deflection. Page 180 Appendix A • Volume 2 The unit weight of snow on roofs, γ, obtained from measurements at a number of weather stations across Canada varied from about 1.0 to 4.5 kN/m3. An average value for use in design in lieu of better local data is γ = 3.0 kN/m3. In some locations the unit weight of snow may be considerably greater than 3.0 kN/m 3. Such locations include regions where the maximum snow load on the roof is reached only after contributions from many snowstorms, coastal regions, and regions where winter rains are considerable and where a unit weight as high as 4.0 kN/m 3 may be appropriate.

Many platforms are subject to both occupancy loads and snow loads. These include balconies, decks, verandas, flat roofs over garages and carports. Where such a platform, or a segregated area of such a platform, serves a single dwelling unit, it must be designed for the greater of either the specified snow load or an occupancy load of 1.9 kPa. Where the platform serves more than one single dwelling unit or an occupancy other than a residential occupancy, higher occupancy loads will apply, as specified in Table 4.1.5.3.

Typical residential roofs are framed with roof trusses and the ceiling is insulated. Residential trusses are placed at 600 mm on centre with web members joining top and bottom chords. Lateral web bracing is installed perpendicular to the span of the trusses. As a result, there is limited room for movement inside the attic or roof space or for storage of material. Access hatches are generally built to the minimum acceptable dimensions, further limiting the size of material that can be moved into the attic or roof space. With exposed insulation in the attic or roof space, access is not recommended unless protective clothing and breathing apparatus are worn. Thus, the attic or roof space is recognized as uninhabitable and loading can be based on actual dead load. In emergency situations or for the purpose of inspection, it is possible for a person to access the attic or roof space without over-stressing the truss or causing damaging deflections. A-Table 9.4.4.1. Classification of Soils. Sand or gravel may be classified by means of a picket test in which a 38 mm by 38 mm (2" x 2") picket bevelled at the end at 45° to a point is pushed into the soil. Such material is classified as “dense or compact” if a man of average weight cannot push the picket more than 200 mm into the soil and “loose” if the picket penetrates 200 mm or more. Clay and silt may be classified as “stiff” if it is difficult to indent by thumb pressure, “firm” if it can be indented by moderate thumb pressure, “soft” if it can be easily penetrated by thumb pressure, where this test is carried out on undisturbed soil in the wall of a test pit.

In susceptible soils, changes in temperature or moisture content can cause significant expansion and contraction. Soils containing pyrites can expand simply on exposure to air. Expansion and Contraction due to Moisture Clay soils are most prone to expansion and contraction due to moisture. Particularly wet seasons can sufficiently increase the volume of the soil under and around the structure to cause heaving of foundations and floors-on-ground, or cracking of foundation walls. Particularly dry seasons or draw-down of water by fast-growing trees can decrease the volume of the soil supporting foundations and floors-on-ground, thus causing settling. Frost Heave Frost heave is probably the most commonly recognized phenomenon related to freezing soil. Frost heave results when moisture in frost-susceptible soil (clay and silt) under the footings freezes and expands. This mechanism is addressed by requirements in Section 9.12. regarding the depth of excavations. Appendix A • Volume 2 Page 181 Ice Lenses When moisture in frost-susceptible soils freezes, it forms an ice lens and reduces the vapour pressure in the soil in the area immediately around the lens. Moisture in the ground redistributes to rebalance the vapour pressures providing more moisture in the area of the ice lens. This moisture freezes to the lens and the cycle repeats itself. As the ice lens grows, it exerts pressure in the direction of heat flow. When lenses form close to foundations and heat flow is toward the foundation - as may be the case with unheated crawl spaces or open concrete block foundations insulated on the interior- the forces may be sufficient to crack the foundation. Adfreezing Ice lenses can adhere themselves to cold foundations. Where heat flow is essentially upward, parallel to the foundation, the pressures exerted will tend to lift the foundation. This may cause differential movement or cracking of the foundation. Heat loss through basement foundations of cast-in-place concrete or concrete block insulated on the exterior appears to be sufficient to prevent adfreezing. Care must be taken where the foundation does not enclose heated space or where open block foundations are insulated on the interior. The installation of semi-rigid glass fibre insulation has demonstrated some effectiveness as a separation layer to absorb the adfreezing forces. Pyrites Pyrite is the most common iron disulphide mineral in rock and has been identified in rock of all types and ages. It is most commonly found in metamorphic and sedimentary rock, and especially in coal and shale deposits. Weathering of pyritic shale is a chemical-microbiological oxidation process that results in volume increases that can heave foundations and floors-on-ground. Concentrations of as little as 0.l% by weight have caused heaving. Weathering can be initiated simply by exposing the pyritic material to air. Thus, building on soils that contain pyrites in concentrations that will cause damage to the building should be avoided, or measures should be taken to remove the material or seal it. Material containing pyrites should not be used for backfill at foundations or for supporting foundations or floors-on- ground. Where it is not known if the soil or backfill contains pyritic material in a deleterious concentration, a test is available to identify its presence and concentration. References: (1) Legget, R.F. and Crawford, C.B. Trees and Buildings. Canadian Building Digest 62, Division of Building Research, National Research Council Canada, Ottawa, 1965. (2) Hamilton, J.J. Swelling and Shrinking Subsoils. Canadian Building Digest 84, Division of Building Research, National Research Council Canada, Ottawa, 1966. (3) Hamilton, J.J. Foundations on Swelling and Shrinking Subsoils. Canadian Building Digest 184, Division of Building Research, National Research Council Canada, Ottawa, 1977. (4) Penner, W., Eden, W.J., and Gratten-Bellew, P.E. Expansion of Pyritic Shales. Canadian Building Digest 152, Division of Building Research, National Research Council Canada, Ottawa, 1975. (5) Swinton, M.C., Brown, W.C., and Chown, G.A. Controlling the Transfer of Heat, Air and Moisture through the Building Envelope. Small Buildings - Technology in Transition, Building Science Insight '90, Institute for Research in Construction, National Research Council Canada, Ottawa, 1990.

The prescriptive solutions provided in Part 9 relating to footings and foundation walls only account for the loads imposed by drained earth. Drained earth is assumed to exert a load equivalent to the load that would be exerted by a fluid with a density of 480 kg/m3. The prescriptive solutions do not account for surcharges from saturated soil or additional loads from heavy objects located adjacent to the building. Where such surcharges are expected, the footings and foundation walls must be designed and constructed according to Part 4. Page 182 Appendix A • Volume 2

If a room draws natural light and natural ventilation from another area, the opening between the two areas must be large enough to effectively provide sufficient light and air. This is why a minimum opening of 3 m2 is required, or the equivalent of the area of a set of double doors. The effectiveness of the transfer of light and air also depends on the size of the transfer opening in relation to the size of the dependent room; in measuring the area of the wall separating the two areas, the whole wall on the side of the dependent room should be considered, not taking into account offsets that may be in the surface of the wall. The opening does not necessarily have to be in the form of a doorway; it may be an opening at eye level. However, if the dependent area is a bedroom, provision must be made for the escape window required by Article 9.9.10.1. to fulfill its safety function. This is why a direct passage is required between the bedroom and the other area; the equivalent of at least a doorway is therefore required for direct passage between the two areas.

This provision for future attachment of grab bars in the main bathroom of a residential occupancy including houses requires the installation of suitable blocking in the stud wall. Sentence 9.31.2.3.(1) specifies the required load resistance. Also, see Appendix Note A-3.3.4.9.(1).

Standard CAN/CGSB-82.6-M, “Doors, Mirrored Glass, Sliding or Folding, Wardrobe”, covers mirrored glass doors for use on reach-in closets. It specifies that such doors are not to be used for walk-in closets.

Tables 9.6.1.3.-A to 9.6.1.3.-F are based on CAN/CGSB-12.20-M, “Structural Design of Glass for Buildings”, and the wind load provisions in Article 4.1.7.3. The maximum glass area values given in these Tables are intended to be equal to or smaller than those that would be determined using the standard and wind load provisions directly to design for each individual case. A-Table 9.6.1.3.-G Glass in Doors. Maximum areas in Table 9.6.1.3.-G for other than fully tempered glazing are cut off at 1.50 m 2, as this would be the practical limit after which safety glass would be required by Sentence 9.6.1.4.(2).

The total prevention of condensation on the surfaces of fenestration products is difficult to achieve and, depending on the design and construction of the window or door, may not be absolutely necessary. Clause 9.7.3.2.(1)(a) therefore requires that condensation be minimized, which means that the amount of moisture that condenses on the inside surface of a window, door or skylight, and the frequency at which this occurs, must be limited. The occurrence of such condensation must be sufficiently rare, the accumulation of any water must be sufficiently small, and drying must be sufficiently rapid to prevent the deterioration of moisture-susceptible materials and the growth of fungi.

Canadian Requirements in the Harmonized Standard In addition to referencing the Canadian Supplement, CSA A440S1, “Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS - North American Fenestration Standard/Specification for Windows, Doors, and Skylights,” the Harmonized Standard, AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS - North American Fenestration Standard/ Specification for Windows, Doors, and Skylights,” contains some Canada-specific test criteria. Appendix A • Volume 2 Page 183 Standards Referenced for Excluded Products Clause 1.1, General, of the Harmonized Standard defines the limits to the application of the standard with respect to various types of fenestration products. A list of exceptions to the application statement identifies a number of standards that apply to excluded products. Compliance with those standards is not required by the Code; the references are provided for information purposes only. Label Indicating Performance and Compliance with Standard The Canadian Supplement requires that a product’s performance ratings be indicated on a label according to the designation requirements in the Harmonized Standard and that the label include • design pressure, where applicable, • negative design pressure, where applicable, • water penetration test pressure, and • the Canadian air infiltration and exfiltration levels. It should be noted that, for a product to carry a label in Canada, it must meet all of the applicable requirements of both the Harmonized Standard and the Canadian Supplement, including the forced entry requirements. Water Penetration Resistance For the various performance grades listed in the Harmonized Standard, the corresponding water penetration resistance test pressures are a percentage of the design pressure. For R-class products, water penetration resistance test pressures are 15% of design pressure. In Ontario, driving rain wind pressures (DRWP) have been determined for the locations listed in MMAH Supplementary Standard SB-1. To achieve equivalent levels of water penetration resistance for all locations, the Canadian Supplement includes a provision for calculating specified DRWP at the building site considering building exposure. Specified DRWP values are, in some cases, greater than 15% of design pressure and, in other cases, less than 15% of design pressure. For a fenestration product to comply with the Code, it must be able to resist the structural and water penetration loads at the building site. Reliance on a percentage of design pressure for water penetration resistance in the selection of an acceptable fenestration product will not always be adequate. Design pressure values are reported on a secondary designator, which is required by the Canadian Supplement to be affixed to the window. The DRWP given in the Canadian Supplement should be used for all products covered in the scope of the Harmonized Standard. Uniform Load Structural Test The Harmonized Standard specifies that fenestration products be tested at 150% of design pressure for wind (specified wind load) and that skylights and roof windows be tested at 200% of design pressure for snow (specified snow load). With the change in the 2006 Building Code to a 1-in-50 return period for wind load, a factor of 1.4 rather than 1.5 is now applied for wind. The Building Code has traditionally applied a factor of 1.5 rather than 2.0 for snow. Incorporating these lower load factors into the Code requirements for fenestration would better reflect acceptable minimum performance levels; however, this has not been done in order to avoid adding complexity to the Code, to recognize the benefits of Canada-US harmonization, and to recognize that differentiation of products that meet the Canadian versus the US requirements would add complexity for manufacturers, designers, specifiers and regulatory officials. Condensation Resistance The Harmonized Standard identifies three test procedures that can be used to determine the condensation resistance of windows and doors. Only the physical test procedure given in CSA A440.2, which is referenced in Table 9.7.3.3., can be used to establish Temperature Index (I) values. Computer simulation tools can also be used to estimate the relative condensation resistance of windows, but these methods employ different expressions of performance known as Condensation Resistance Factors (CR). I and CR values are not interchangeable. Page 184 Appendix A • Volume 2 Where removable multiple glazing panels (RMGP) are installed on the inside of a window, care should be taken to hermetically seal the RMGP against the leakage of moisture-laden air from the interior into the cavity on the exterior of the RMGP because the moisture transported by the air could lead to significant condensation on the interior surface of the outside glazing. Basement Windows Clause 12.4.2, Basement Windows, of the Harmonized Standard refers to products that are intended to meet Code requirements for ventilation and emergency egress. The minimum test size of 800 mm x 360 mm (total area of 0.288 m2) specified in the standard will not provide the minimum openable area required by the Code for bedrooms (i.e. 0.35 m 2 with no dimension less than 380 mm) and the means to provide minimum open area identified in the standard is inconsistent with the requirements of the Code (see Subsection 9.9.10. for bedroom windows). The minimum test size specified in the standard will also not provide the minimum ventilation area of 0.28 m 2 required for non-heating-season natural ventilation (see Article 9.32.2.2.). Greenhouse Windows Greenhouse-type windows feature a sloped, roof-like top portion, which is subjected to the same snow loads as roofs. The Canadian Supplement only applies the snow load calculation to skylights, which do not include greenhouse windows according to the definition for skylights given in the Canadian Supplement and the Harmonized Standard. Where such windows are used, it is recommended that snow loads on the top portion of the window be taken into account. Performance of Doors: Limited Water Ingress Control. While the control of precipitation ingress is a performance requirement for exterior doors, side-hinged doors can comply with the referenced standard. AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS – North American Fenestration Standard/ Specification for Windows, Doors, and Skylights”, when tested at a pressure differential of 0 Pa (0.0 psf) or higher, but less than the minimum test pressure required for the indicated performance class and performance grade. Such doors are identified with a “Limited Water” (LW) rating on the product label. There is no restriction on the use of side-hinged doors having a limited water designation when the tested water penetration resistance of such doors is equal to or greater than the specified Driving Rain Wind Pressure for the building location, as stated in Clause A.4.4 of CSA A440S1, “Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440, NAFS – North American Fenestration Standard/Specification for Windows, Doors, and Skylights”. When an LW door does not have sufficient water penetration resistance for the building location, Clause B.5.3.3 of CSA A440S1 states that these doors should only be used and installed in a protected location, such as under a porch roof. Other protected locations would be behind a storm door, or a door separating conditioned space from unconditioned space, such as in cold storage rooms. The Exposure Nomograph in Annex A of CAN/CSA-A440.4, “Window, Door, and Skylight Installation”, provides an acceptable method to determine whether a door is considered protected, which depends on overhang ratio, and the terrain and moisture index of the building location. A door with an LW rating and a low exposure could provide acceptable water penetration resistance. However, given that the Exposure Nomograph in Annex A of CAN/CSA-A440.4 does not account for the intensity of wind driven rain, a door with an LW rating may not provide appropriate protection in some locations. In such cases, the risk of water penetration may remain the same as if the overhead protection were not provided.

There is no mandatory requirement that special glass be used in doors or sidelights, primarily because of cost. It is, however, a common method of forced entry to break glass in doors and sidelights to gain access to door hardware and unlock the door from the inside. Although insulated glass provides increased resistance over single glazing, the highest resistance is provided by laminated glass. Tempered glass, while stronger against static loads, is prone to shattering under high, concentrated impact loads. Laminated glass is more expensive than annealed glass and must be used in greater thicknesses. Figure A-9.7.5.2.(1) shows an insulated sidelight made of one pane of laminated glass and one pane of annealed glass. This method reduces the cost premium that would result if both panes were laminated. Appendix A • Volume 2 Page 185 Consideration should be given to using laminated glazing in doors and accompanying sidelights regulated by Article 9.6.1.3., in windows located within 900 mm of locks in such doors, and in basement windows. Underwriters' Laboratories of Canada have produced ULC-S332, “Standard for Burglary Resisting Glazing Material”, which provides a test procedure to evaluate the resistance of glazing to attacks by thieves. While it is principally intended for plate glass show windows, it may be of value for residential purposes. Figure A-9.7.5.2.(1) Combined Laminated / Annealed Glazing

This Sentence designates standard ASTM F476, “Standard Test Methods for Security of Swinging Door Assemblies” as an alternate to compliance with the prescriptive requirements for doors and hardware. The annex to the standard provides four security classifications, with acceptance criteria, depending on the type of building and the crime rate of the area in which it is located. The Building Code has only specified Grade 10, the minimum level. The annex suggests the following guidelines be followed when selecting security levels for door assemblies: Grade 10: This is the minimum security level and is quite adequate for single-family residential buildings located in stable, low-crime areas. Grade 20: This is the low-medium security level and is designed to provide security for residential buildings located in average crime-rate areas and for apartments in both low and average crime-rate areas. Grade 30: This is the medium-high security level and is designed to provide security for residential buildings located in higher than average crime-rate areas or for small commercial buildings in average or low crime-rate areas. Grade 40: This is the high security level and is designed for small commercial buildings located in high crime-rate areas. This level could also be used for residential buildings having an exceptionally high incidence of semi- skilled burglary attacks. All these grades satisfy the Code and can be considered for use where a higher level of security is desired or warranted. 9.7.5.2.(6) Door Fasteners. The purpose of the requirement for 30 mm screw penetration into solid wood is to prevent the door from being dislodged from the jamb due to impact forces. It is not the intent to prohibit other types of hinges or strikeplates that are specially designed to provide equal or greater protection.

Methods of satisfying this Sentence include either using non-removable pin hinges or modifying standard hinges by screw fastening a metal pin in a screw hole in one half of the top and bottom hinges. When the door is closed, the projecting portion of the pin engages in the corresponding screw hole in the other half of the hinge and then, even if the hinge pin is taken out, the door cannot be removed. Page 186 Appendix A • Volume 2

Although this Sentence only applies to windows within 2 m of adjacent ground level, certain house and site features, such as balconies or canopy roofs, allow for easy access to windows at higher elevations. Consideration should be given to specifying break-in resistant windows in such locations. This Sentence does not apply to windows that do not serve the interior of the dwelling unit, such as windows to garages, sun rooms or greenhouses, provided connections between these spaces and the dwelling unit are secure. One method that is often used to improve the resistance of windows to forced entry is the installation of metal “security bars”. However, while many such installations are effective in increasing resistance to forced entry, they may also reduce or eliminate the usefulness of the window as an exit in case of fire or other emergency that prevents use of the normal building exits. Indeed, unless such devices are easily openable from the inside, their installation in some cases would contravene the requirements of Article 9.9.10.1., which requires every bedroom that does not have an exterior door to have at least one window that is large enough and easy enough to open that it can be used as an exit in case of emergency. Thus an acceptable security bar system should be easy to open from the inside while still providing increased resistance to entry from the outside.

Table A-9.8.3.1. Permitted Stair Configurations Configuration of Stair Treads Location/Use of Flight with a mix of Stairs Straight Flight with Curved Flight with Winders Rectangular Treads Spiral Stairs Rectangular Treads Tapered Treads and Tapered Treads Stairs within Permitted(1) Permitted(2) Permitted(3) Permitted(4) Permitted(5) dwelling units Public stairs Permitted(1) Permitted(6) Not permitted Not permitted Permitted(5) Exit stairs Permitted(1) Permitted(6) Not permitted Not permitted Not permitted Notes to Table A-9.8.3.1.: 1. See Articles 9.8.4.1. and 9.8.4.2. 2. See Article 9.8.4.1. and 9.8.4.3. 3. See Article 9.8.4.6. 4. See Article 9.8.4.5. 5. See Sentence 9.8.4.7. 6. See Articles 3.4.6.9. and 9.8.4.3. Appendix A • Volume 2 Page 187

The Code distinguishes four principal types of stair treads: • rectangular treads, which are found in straight flights; • tapered treads are found in curved flights; • winders are described in Appendix Note A-9.8.4.6.; and • spiral stairs are described in Appendix Note A-9.8.4.7. See Figure A-9.8.4.-A. Figure A-9.8.4.-A Types of Treads Articles 9.8.4.1. to 9.8.4.8. specify various dimensional limits for steps. Figure A-9.8.4.-B illustrates the elements of a step and how these are to be measured. Figure A-9.8.4.-B Elements of Steps and their Measurement Page 188 Appendix A • Volume 2

The safest method of incorporating a change in the direction of a stair is to use a landing. Within a dwelling unit, however, where occupants are familiar with their environment, winders are an acceptable method of reducing the amount of floor area devoted to the stair and have not been shown to be more hazardous than a straight run of steps. Nevertheless, care is required to ensure that winders are as safe as possible. Experience has shown that 30° winders are the best compromise and require the least change in the natural gait of the stair user; 45° winders are also acceptable, as they are wider. The Code permits winders to turn through any angle between 30° and 45°, inclusive. This allows winder-type stairs to change direction through any angle between 30° (1 winder) and 90° (2 or 3 winders).

A spiral stair is typically described as a stair with a circular plan having uniform treads that radiate from and wind around a common central post or supporting column. In the context of the Code, the term “spiral stair” is used to describe any stair where: a) the plan of the treads forms part or all of the circle, b) the maximum stair width and tread depth are less than those required for curved stairs, and c) the maximum riser height is greater than that permitted in all other stair configurations. Figure A-9.8.4.7. Spiral Stairs Appendix A • Volume 2 Page 189

A sloped or bevelled edge on tread nosings will make the tread more visible through light modelling. The sloped portion of the nosing must not be too wide so as to reduce the risk of slipping of the foot. See Figure A-9.8.4.-B.

A door that swings away from a stair exposes sufficient floor space to act as a landing for users before descending the stairs.

The intent of Sentence 9.8.7.1.(2) is that handrails be installed in relation to the required exit width only, regardless of the actual width of the stair and ramp. The required handrails are provided along the assumed natural path of travel to and from the building.

The guidance and support provided by handrails is particularly important at the beginning and end of ramps and flights of stairs and at changes in direction such as at landings and winders. The intent of the requirement in Sentence (2) for handrails to be continuous throughout the length of the stair is that the handrail be continuous from the bottom riser to the top riser of the stair. (See Figure A-9.8.7.2.) For stairs or ramps serving a single dwelling unit, the intent of the requirement for handrails to be continuous throughout the length of the flight is that the handrail be continuous from the bottom riser to the top riser of the flight. The required handrail may start back from the bottom riser only if it is supported by a newel post or volute installed on the bottom tread. (See Figure A-9.8.7.2.) With regard to stairs serving a house or an individual dwelling unit, the handrail may terminate at landings. In the case of stairs within dwelling units that incorporate winders, the handrail should be configured so that it will in fact provide guidance and support to the stair user throughout the turn through the winder. Page 190 Appendix A • Volume 2 Figure A-9.8.7.2. Continuity of Handrails at the Top and Bottom of Stairs and Flights of Stairs Notes to Figure A-9.8.7.2.: (1) See Article 9.8.7.1. to determine the number of handrails required. Some stairs will require only one, while some will require two or more.

Handrails are required to be installed so as not to obstruct pedestrian travel. To achieve this end, the rail should not extend so far into a hallway as to reduce the clear width of the hallway to less than the required width. Where the stair terminates in a room or other space, likely paths of travel through that room or space should be assessed to ensure that any projection of the handrail beyond the end of the stair will not interfere with pedestrian travel. As extensions of handrails beyond the first and last riser are not required in dwelling units [See Sentence 9.8.7.3.(2)] and as occupants of dwellings are generally familiar with their surroundings, the design of dwellings would not generally be affected by this requirement. Handrails are also required to terminate in a manner that will not create a safety hazard to blind or visually impaired persons, children whose heads may be at the same height as the end of the rail, or persons wearing loose clothing or carrying items that might catch on the end of the rail. One approach to reducing potential hazards is returning the handrail to a wall, floor or post. Again, within dwelling units, where occupants are generally familiar with their surroundings, returning the handrail to a wall, floor or post may not be necessary. For example, where the handrail is fastened to a wall and does not project past the wall into a hallway or other space, a reasonable degree of safety is assumed to be provided; other alternatives may provide an equivalent level of protection. Appendix A • Volume 2 Page 191

As noted in Appendix Note A-9.8.7.2., the guidance and support provided by handrails is particularly important at the beginning and end of ramps and flights of stairs and at changes in direction. The extended handrail provides guidance and allows users to steady themselves upon entering or leaving a ramp or flight of stairs. Such extensions are particularly useful to visually-impaired persons, and persons with physical disabilities or who are encumbered in their use of the stairs or ramp.

Figure A-9.8.7.4. illustrates how to measure handrail height. Figure A-9.8.7.4. Measuring Handrail Height

Handrails are intended to provide guidance and support to stair users. To fulfil this intent, handrails must be “graspable”. The graspable portion of a handrail should allow a person to comfortably and firmly grab hold by allowing their fingers and thumb to curl under part or all of the handrail. Where the configuration or dimensions of the handrail do not allow a person’s fingers and thumb to reach the bottom of it, recesses that are sufficiently wide and deep to accommodate a person’s fingers and thumb must be provided on both sides of the handrail, at the bottom of the graspable portion, which must not have sharp edges.

Handrails are intended to provide guidance and support to the stair user and to arrest falls. The loads on handrails may therefore be considerable. The attachment of handrails serving a house or an individual dwelling unit may be accepted on the basis of experience, structural design, or the prescriptive requirements of Sentence 9.8.7.7.(2). Page 192 Appendix A • Volume 2

The requirements relating to guards stated in Part 9 are based on the premise that, wherever there is a difference in elevation of 600 mm or more between two floors, or between a floor or other surface to which access is provided for other than maintenance purposes and the next lower surface, the risk of injury in a fall from the higher surface is sufficient to warrant the installation of some kind of barrier to reduce the chances of such a fall. A wall along the edge of the higher surface will obviously prevent such a fall, provided the wall is sufficiently strong that a person cannot fall through it. Where there is no wall, a guard must be installed. Because guards clearly provide less protection than walls, additional requirements apply to guards to ensure that a minimum level of protection is provided. These relate to the characteristics described in Appendix Notes A-9.8.8.3., A-9.8.8.5.(1) and (2), A-9.8.8.5.(3) and A-9.8.8.6.(1). Examples of such surfaces where the difference in elevation could exceed 600 mm and consequently where guards would be required include, but are not limited to, landings, porches, balconies, mezzanines, galleries, and raised walkways. Especially in exterior settings, surfaces adjacent to walking surfaces, stairs or ramps often are not parallel to the walking surface or the surface of the treads or ramps. Consequently, the walking surface, stair or ramp may need protection in some locations but not in others. (See Figure A-9.8.8.1.) In some instances, grades are artificially raised close to walking surfaces, stairs or ramps to avoid installing guards. This provides little or no protection for the users. That is why the requirements specify differences in elevation not only immediately adjacent to the construction but also for a distance of 1 200 mm from it by requiring that the slope of the ground be within certain limits. (See Figure A-9.8.8.1.) Figure A-9.8.8.1. Required Locations of Guards

The primary intent of the requirement is to minimize the likelihood of small children falling significant heights from open windows. Reflecting reported cases, the requirement applies to openable windows in dwelling units and generally those located on the second floor or higher of residential or mixed-use buildings. Once cracked open, some openable windows can be opened further by simply pushing on the openable part of the window. Care must be taken in selecting windows, as some with special operating hardware can still be opened further by simply pushing on the window or by deactivating a spring-loaded button or other mechanism that is not considered a window opening control device (WOCD) that could be inadvertently operated by a young child. A technical description of WOCDs can be found in ASTM F2090, “Standard Specification for Window Fall Prevention Devices With Emergency Escape (Egress) Release Mechanisms.” Examples of WOCDs that can limit window openings to a maximum of 100 mm as required by Clause 9.8.8.1.(4)(b) include, but are not limited to, a fixed-stop lever, a fixed-length cable and a fixed-position stop block. It is important to note that rotary opening mechanisms cannot limit window openings to 100 mm as required by Clause 9.8.8.1.(4)(b) and that windows with such mechanisms cannot act as guards as required by Clause 9.8.8.1.(4)(a), even when the crank handle is removed. Similarly, awning windows with scissor hardware may not keep the window from swinging open once it is unlatched. Hopper windows would be affected only if an opening is created at the bottom as well as at the top of the window. The requirement will impact primarily on the use of sliding windows which do not incorporate devices in their construction that can be used to limit the openable area of the window. Appendix A • Volume 2 Page 193 The 100 mm opening limit stated in Sentence 9.8.8.1.(4) is recognized as the maximum opening size required to protect small children from falling through open windows. The minimum 900 mm height of the openable portion of windows required by Sentence 9.8.8.1.(5) corresponds to the minimum height of guards required by Sentence 9.8.8.3.(2) as a means of fall protection in residential occupancies.

Guards must be constructed so as to be strong enough to protect persons from falling under normal use. Many guards installed in dwelling units or on exterior stairs serving one or two dwelling units have demonstrated acceptable performance over time. The loading specified in the first row of Table 9.8.8.2. is intended to be consistent with the performance provided by these guards. Guards constructed in accordance with MMAH Supplementary Standard SB-7 are deemed to meet the requirements of Article 9.8.8.2. The load on guards within dwelling units, or on exterior guards serving not more than two dwelling units, is to be imposed over an area of the guard such that, where standard balusters are used and installed at the maximum 100 mm spacing permitted for required guards, 3 balusters will be engaged. Where the balusters are wider, only two may be engaged unless they are spaced closer together. Where the guard is not required, and balusters are installed more than 100 mm apart, fewer balusters may be required to carry the imposed load.

Guard heights are generally based on the waist heights of average persons. Generally, lower heights are permitted in dwelling units because the occupants become familiar with the potential hazards, and situations which lead to pushing and jostling under crowded conditions are less likely to arise.

The risk of falling through a guard is especially prevalent for children. Therefore, the requirements are stringent for guards in all buildings except industrial buildings, where children are unlikely to be present except under strict supervision.

The requirements to prevent children falling through guards also serve to provide adequate protection against this problem. However, guards are often installed where they are not required by the Code; i.e., in places where the difference in elevation is less than 600 mm. In these cases, there is no need to require the openings between balusters to be less than 100 mm. However, there is a range of openings between 100 mm and 200 mm in which children can get their heads stuck. Therefore, openings in this range are not permitted except in buildings of industrial occupancy, where children are unlikely to be present except under strict supervision.

Guards are sometimes constructed with horizontal or near-horizontal members between balusters such that a ladder effect is achieved. This can be very tempting for young children to climb, thus exposing themselves to risk of falling over the guard. Such construction is not permitted for required guards in buildings of residential occupancy.

A tactile indicator strip signals a warning to people with no or low vision that they are approaching a change in level. The strip is set back from the leading edge of the stair to provide sufficient warning of the change in level in advance. Also, see Appendix Note A-3.4.6.1.(2). Page 194 Appendix A • Volume 2

Figure A-9.9.4.5.(1) Protection of Openings in Exterior Walls of Exits

Subsection 9.9.8. requires that some floor areas have more than one exit. The intent is to ensure that, if one exit is made untenable or inaccessible by a fire, or its exterior door is blocked by an exterior incident, one or more other exits will be available to permit the occupants to escape. However, if the exits are close together, all exits might be made untenable or inaccessible by the same fire. Sentence 9.9.8.4.(1), therefore, requires at least two of the exits to be located remotely from each other. This is not a problem in many buildings falling under Part 9. For instance, apartment buildings usually have exits located at either end of long corridors. However, in other types of buildings (e.g., dormitory and college residence buildings) this is often difficult to accomplish and problems arise in interpreting the meaning of the word “remote”. Article 3.4.2.3. is more specific, generally requiring the distance between exits to be one half the diagonal dimension of the floor area or at least 9 m. However, it is felt that such criteria would be too restrictive to impose on the design of all the smaller buildings which are governed by Part 9. Nevertheless, the exits should be placed as far apart as possible and the Part 3 criteria should be used as a target. Designs in which the exits are so close together that they will obviously both become contaminated in the event of a fire are not acceptable. Appendix A • Volume 2 Page 195

Although the minimum opening dimensions required for height and width are 380 mm, a window opening that is 380 mm by 380 mm would not comply with the minimum area requirements. (See Figure A-9.9.10.1.(1)) Figure A-9.9.10.1.(1) Window Opening Areas and Dimensions

Sentence 9.9.10.1.(2) requires every floor level which contains a bedroom to have at least one window or door to the exterior that is large enough and easy enough to open that it can be used as an exit in case of a fire. However, Article 9.9.10.1. does not set a maximum sill height for such a window in a basement area. It is recommended that the sills of windows intended for use as emergency exits from basement bedroom areas be not higher than 1.5 m above the floor. Sometimes it is difficult to avoid having the sill higher than this; e.g., skylights, windows in basement bedrooms. In these cases, it is recommended that access to the window be improved by some means such as built-in furniture installed below the window. (See Figure A-9.9.10.1.(2)) Figure A-9.9.10.1.(2) Built-in Furniture to Improve Access to a Window Page 196 Appendix A • Volume 2

Sentence 9.9.10.1.(3) specifies that there must be a minimum clearance of 550 mm in front of designated escape windows to allow persons to escape a basement bedroom in an emergency. This specified minimum clearance is consistent with the minimum required width for means of egress from a floor area (see Article 9.9.5.5.) and the minimum required width for path of travel on exit stairs (see Article 9.9.6.1.). It is considered the smallest acceptable clearance between the escape window and the facing wall of the window well that can accommodate persons trying to escape a bedroom in an emergency given that they are not moving straight through the window but must move outward and up, and must have sufficient space to change body orientation. Once this clearance is provided, no additional clearance is needed for windows with sliders, casements, or inward-opening awnings. However, for windows with outward-opening awnings, additional clearance is needed to provide the required 550 mm beyond the outer edge of the sash. (See Figure A-9.9.10.1.(3)) Depending on the likelihood of snow accumulation in the window well, it could be difficult — if not impossible — to escape in an emergency. The window well should be designed to provide sufficient clear space for a person to get out the window and then out the well, taking into account potential snow accumulation. Hopper windows (bottom-hinged operators) should not be used as escape windows in cases where the occupants would be required to climb over the glass. Figure A-9.9.10.1.(3) Windows Providing a Means of Escape that Open into a Window Well.

The identification of floors and other signs intended to facilitate orientation for persons with vision loss should offer maximum colour contrast to be effective. For this reason, it is recommended that white on black or black on white be used, as this combination produces the best legibility. It is also recommended that the sign surfaces be processed to prevent glare.

Some provisions captured by the cross-reference to Part 3 go beyond the intended application of the cross-reference. In the context of the cross-reference, Subsections Articles 3.2.5.8 to 3.2.5.15., 3.2.5.17. and 3.2.5.18. apply only where sprinkler, standpipe or hose systems are installed in a Part 9 building, whether the installation is voluntary or for the purpose of complying with the provisions in Part 9. Provisions in Part 3 that identify buildings or spaces in which these systems are to be installed do not apply. Appendix A • Volume 2 Page 197

Part 6 refers to NFPA 96, “Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations”, which in turn references “Commercial Cooking Equipment”. However, the deciding factor as to whether or not NFPA 96 applies is the potential for production of grease-laden vapours and smoke, rather than the type of equipment used. While NFPA 96 does not apply to domestic equipment for normal residential family use, it should apply to domestic equipment used in commercial, industrial, institutional and similar cooking applications where the potential for the production of smoke and grease-laden vapours exceeds that for normal residential family use.

The Tables found in MMAH Supplementary Standard SB-3 may be used to select building assemblies for compliance with Article 9.10.3.1. and Subsection 9.11.2. Assembles not listed in those Tables are equally acceptable provided their fire and sound resistance can be demonstrated to meet the above-noted requirements on the basis of tests referred to in 9.10.3.1. and 9.11.1. or by using the data in MMAH Supplementary Standard SB-2.

Mezzanines increase the occupant load and the fire load of the storey of which they are part. To take the added occupant load into account for the purpose of evaluating other requirements that are dependent on this criteria, their floor area is added to the floor area of the storey.

Light-frame walls, columns, arches and beams do not include heavy timber elements or masonry or concrete construction.

The continuity of a smoke-tight barrier where it abuts another smoke-tight barrier, a floor, a ceiling or a wall assembly is maintained by constructing smoke-tight joints (e.g., through the design of the gypsum board joints and framing members) or by filling all openings at the juncture of the assemblies with a material that will ensure the integrity of the smoke-tight barrier at that location.

Sentence 9.10.9.6.(1), like Article 3.1.9.1., is intended to ensure that the integrity of fire separations is maintained where they are penetrated by various types of service equipment. For buildings regulated by Part 3, firestop materials used to seal openings around building services, such as pipes, ducts and electrical outlet boxes, must meet a minimum level of performance demonstrated by standard test criteria. A similar approach is applied to buildings regulated by Part 9 when complying with Clause 9.10.9.6.(1)(a). In addition, because of the type of construction normally used for Part 9 buildings, it is assumed that the requirement to maintain the integrity of the fire separation is satisfied by the use of generic firestop materials such as mineral wool, gypsum plaster or Portland cement mortar to seal penetrations in accordance with Clause 9.10.9.6.(1)(c). The use of the terms “tightly fitted” and “cast in place” in Clause 9.10.9.6.(1)(b) is intended to emphasize that there are to be no gaps between the building service or penetrating item and the membrane or assembly it penetrates.

Outlet boxes that exceed the area limits specified in Sentence 9.10.9.8.(2) or (3) do not need to be sealed at the penetration by a firestop in accordance with Sentence 9.10.9.8.(1) if they are installed in a recessed enclosure with a construction that maintains the continuity of the fire-resistance rating of the fire separation or membrane. Any penetrations of the enclosure by wiring or cables must comply with all applicable requirements. Page 198 Appendix A • Volume 2

The fire block material separating the outlet box from the adjacent space within the assembly should span the framing members such that all four sides and the back of the outlet box are enclosed by a membrane or framing member conforming to Article 9.10.16.3. Any penetrations of the enclosure by wiring or cables must comply with all applicable requirements. (See also Note A-3.1.11.7.(7))

The gas-tight barrier between a dwelling unit and an attached garage is intended to provide reasonable protection from carbon monoxide and gasoline fumes entering the dwelling unit. Construction assemblies incorporating an air barrier system will perform adequately with respect to gas tightness, provided reasonable care is exercised where the wall or ceiling is pierced by building services. Where a garage is open to the adjacent attic space above the dwelling unit it serves, a gas-tight barrier in the dwelling unit ceiling will also provide protection. Unit masonry walls forming the separation between a dwelling unit and an adjacent garage should be provided with two coats of sealer or plaster or covered with gypsum wallboard on the side of the wall exposed to the garage. All joints must be sealed to ensure continuity of the barrier. (See also Sentences 9.25.3.3.(3) to (8))

Figure A-9.10.12.4.(1) Protection of Overhang of Common Roof Space

The materials required by this Sentence to be used as protection for soffit spaces in certain locations do not necessarily have to be the finish materials. They can be installed either behind the finishes chosen for the soffits or in lieu of these.

CAN/ULC-S113, “Standard Specification for Wood Core Doors Meeting the Performance Required by CAN/ULC-S104 for Twenty Minute Fire Rated Closure Assemblies” provides construction details to enable manufacturers to build wood core doors that will provide a 20 min fire-protection rating without the need for testing. The Standard requires each door to be marked with (1) manufacturer’s or vendor’s name or identifying symbol, (2) the words “Fire Door”, and (3) a reference to the fire-protection rating of 20 min. Appendix A • Volume 2 Page 199

Minor elements of cladding that is required to be noncombustible are permitted to be of combustible material, provided they are distributed over the building face and not concentrated in one area. Examples of minor combustible cladding elements include door and window trim and some decorative elements.

Subsection 9.10.15. applies to the spatial separation between houses which may contain one dwelling unit above another. The designer has the option of using either Subsection 9.10.14. or Subsection 9.10.15. for the determination of spatial separation requirements for these types of buildings. However, the requirements of these two Subsections cannot be mixed. The buildings to which Subsection 9.10.15. applies include: • traditional individual detached houses with or without a secondary suite, • semi-detached houses (doubles) where each house may contain a secondary suite, • row houses, where any house may contain a secondary suite (see Sentence 9.10.11.2.(1)), and • stacked dwelling units where one of them is a secondary suite. Subsection 9.10.15. does not apply to stacked row houses/townhouses or stacked dwelling units that are not within a house with a secondary suite.

Studies at the National Fire Laboratory of the National Research Council have shown that, where an exposing building face is stepped back from the property line or is at an angle to the property line, it is possible to increase the percentage of glazing in those portions of the exposing building face further from the property line without increasing the amount of radiated energy that would reach the property line in the event of a fire in such a building. Figures A-9.10.15.4.(2)-A to A-9.10.15.4.(2)-C show how Sentences 9.10.15.4.(1) and (2) and 9.10.15.5.(2) could be applied to exposing building faces that are stepped back from or not parallel to the property line. The following procedure can be used to establish the maximum permitted area of glazed openings for such facades: 1. Calculate the total area of the exposing building face, i.e. facade of the fire compartment, as described in the definition of exposing building face. 2. Identify the portions into which the exposing building face is to be divided. It can be divided in any number of portions, not necessarily of equal size. 3. Measure the limiting distance for each portion. The limiting distance is measured along a line perpendicular to the wall surface from the point closest to the property line. 4. Establish the line in Table 9.10.15.4. from which the maximum permitted percentage area of glazed openings will be read. The selection of the line depends on the maximum area of exposing building face for the whole fire compartment, including all portions, as determined in Step 1. 5. On that line, read the maximum percentage area of glazed openings permitted in each portion of the exposing building face according to the limiting distance for that portion. 6. Calculate the maximum area of glazed openings permitted in each portion. The area is calculated from the percentage found applied to the area of that portion. Table 9.10.15.4. is used to determine the maximum area of glazed openings. Therefore, unglazed portions of doors need not be counted, as for other types of buildings. Page 200 Appendix A • Volume 2 Figure A-9.10.15.4.(2)-A Example of Determination of Criteria for the Exposing Building Face of a Staggered Wall of a House Appendix A • Volume 2 Page 201 Figure A-9.10.15.4.(2)-B Example of Determination of Criteria for the Exposing Building Face of a Skewed Wall of a House With Some Arbitrary Division of the Wall Note to Figure A-9.10.15.4.(2)-B: (1) To simplify the calculations, choose the column for the lesser limiting distance nearest to the actual limiting distance. Interpolation for limiting distance is also acceptable and may result in a slightly larger permitted area of glazed openings. Interpolation can only be used for limiting distances greater than 1.2 m. Page 202 Appendix A • Volume 2 Figure A-9.10.15.4.(2)-C Example of Determination of Criteria for the Exposing Building Face of a Skewed Wall of a House With a Different Arbitrary Division of the Wall Note to Figure A-9.10.15.4.(2)-C: (1) To simplify the calculations, choose the column for the lesser limiting distance nearest to the actual limiting distance. Interpolation for limiting distance is also acceptable and may result in a slightly larger permitted area of glazed openings. Interpolation can only be used for limiting distances greater than 1.2 m.

and Systems. A number of provisions captured by the cross-reference to Subsection 3.2.4. address issues already addressed in Subsection 9.10.18. and so are not applicable to Part 9 buildings. For example, Articles 9.10.18.2. and 9.10.18.8. identify the Part 9 buildings where fire alarm systems are required, so Article 3.2.4.1. does not apply. Note that, because the cross-reference relating to sprinkler systems in Sentence 9.10.1.3.(8) refers to conformance with Articles 3.2.5.12. to 3.2.5.15. and Article 3.2.5.17., the requirements of Subsection 3.2.4. regarding electrical supervision and monitoring do not normally apply to sprinkler systems in Part 9 buildings. However, where a sprinkler system is installed in lieu of heat and smoke detectors according to Sentence 9.10.18.4.(3) electrical supervision and monitoring of the sprinkler system must comply with the provisions in Subsection 3.2.4.

Smoke alarms with a visual signalling component can alert people who are deaf, deafened or hard of hearing to the presence of smoke in the dwelling just as the alarm sound provides an alert to people with no or low vision or who are sighted. The visual signal provides an extra level of safety alerts to building residents. Appendix A • Volume 2 Page 203

Statistics have shown that next to kitchen fires, fires originating in bedrooms within dwelling units account for the second highest causes of fire deaths in homes. The requirement for smoke alarms in sleeping rooms (bedrooms) provides early detection and warning of fires originating in sleeping rooms. Smoke alarms located outside sleeping rooms are required as they are better capable of detecting a fire originating outside of the room. A smoke alarm is not required on each level in a split-level dwelling unit as each level does not count as a separate storey. Determine the number of storeys in a split-level dwelling unit and which levels are part of which storey as follows: 1. establish grade, (See definition of “grade” in Sentence 1.4.1.2.(1) of Division A.); 2. identify the first storey, (See definition of “first storey” in Sentence 1.4.1.2.(1) of Division A.); 3. identify the basement, (See definition of “basement” in Sentence 1.4.1.2.(1) of Division A.); 4. identify the second storey and, where applicable, the third storey. Additional Smoke Alarms Outside of Sleeping Areas As a minimum, one smoke alarm is required to be installed on each storey, preferably on the upper level of each one. As noted above, however, when the dwelling unit contains more than one sleeping area, a smoke alarm must be installed to serve each area. Where the sleeping areas are on two levels of a single storey in a split-level dwelling unit, an additional smoke alarm must be installed so that both areas are protected. See Figure A-9.10.19.3.(1). Figure A-9.10.19.3.(1) Two-Storey Split-Level Building Notes to Figure A-9.10.19.3.(1): (1) One smoke alarm required lor each of the basement, first storey and second storey. (2) An additional smoke alarm is required on the lower level of the second storey outside the sleeping rooms.

Electrical regulations may require that separate power sources be provided for smoke alarms in the main dwelling unit and the secondary suite where the units have separate electrical services. In these situations, interconnection of smoke alarms between the units can be achieved through wireless communication.

In addition to other considerations taken into account in the planning of fire department access routes, special variations could be permitted for a house or residential building that is protected with an automatic sprinkler system. The sprinkler system must be designed in accordance with the appropriate NFPA standard and there must be assurance that water supply pressure and quantity are unlikely to fail. These considerations could apply to buildings that are located on the sides of hills Page 204 Appendix A • Volume 2 and are not conveniently accessible by roads designed for firefighting equipment and also to infill housing units that are located behind other buildings on a given property.

The Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code), and Ontario Natural Gas Code address clearances directly above, in front of, behind and beside ranges. Where side clearances are zero, the standards do not address clearances to building elements located both above the level of the range elements or burners and to the side of the appliance. Through reference to the Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code) and the requirements in Articles 9.10.22.2. and 9.10.22.3., the Building Code addresses all clearances. Where clearances are addressed by the Building Code and the Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code) or Ontario Natural Gas Code, conformance with all relevant criteria is achieved by compliance with the most stringent criteria. Installation of Microwave Ovens Over Cooktops The minimum vertical clearances stated in Article 9.10.22.2. apply only to combustible framing, finishes and cabinets. They do not apply to microwave ovens installed over cooktops nor to range hoods. Microwave ovens must comply with CAN/CSA-C22.2 NO. 150, “Microwave Ovens”, which is referenced in the Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code). This standard includes tests to confirm that the appliance will not present a hazard when installed according to the manufacturer’s instructions. Figure A-9.10.22. Clearances from Cooktops to Walls and Cabinetry Appendix A • Volume 2 Page 205

Airborne Sound Airborne sound is transmitted between adjoining spaces directly through the separating wall, floor and ceiling assemblies and via the junctions between these separating assemblies and the flanking assemblies. The Sound Transmission Class (STC) rating describes the performance of the separating wall or floor/ceiling assembly, whereas the Apparent Sound Transmission Class (ASTC) takes into consideration the performance of the separating element as well as the flanking transmission paths. Therefore, from the occupants’ point of view, the best indicator of noise protection between the two spaces is the ASTC rating. As a key principle, it is important to follow a “whole system” approach when designing or constructing assemblies that separate dwelling units because the overall sound performance of walls and floors is also influenced by fire protection measures and the structural design of the assemblies. Likewise, changes to the construction of assemblies to meet sound transmission requirements may have fire and structural implications. Another key principle is that enhancing the performance of the separating element does not automatically enhance the system’s performance. For horizontally adjoining spaces, the separating assembly is the intervening wall and the pertinent flanking surfaces include those of the floor, ceiling, and side wall assemblies that have junctions with the separating wall assembly, normally at its four edges. For each of these junctions, there are a set of sound transmission paths. Figure A-9.11.-A illustrates the horizontal sound transmission paths at the junction of a separating wall with flanking floor assemblies. Figure A-9.11.-A Horizontal Sound Transmission Paths Floor/Wall Junction For vertically adjoining spaces, the separating assembly is the intervening floor/ceiling and the pertinent flanking surfaces include those of the side wall assemblies in the upper and lower rooms that have junctions with the separating floor/ceiling assembly at its edges, of which there are normally four. For each of these junctions, there is a set of sound transmission paths. Figure A-9.11.-B illustrates the vertical sound transmission paths at the junction of a separating floor/ceiling assembly with two flanking wall assemblies. Page 206 Appendix A • Volume 2 Figure A-9.11.-B Vertical Sound Transmission Paths Floor/Wall Junction Control of Sound Leaks The metrics used to characterize the sound transmission performance of assemblies separating dwelling units do not account for the adverse effects of air leaks in those assemblies, which can transfer sound. Sound leaks can occur where a wall meets another wall, the floor, or the ceiling. They can also occur where the wall finish is cut for the installation of equipment or services. The following are examples of measures for controlling sound leaks: • Avoid back-to-back electrical outlets or medicine cabinets; • Carefully seal cracks or openings so structures are effectively airtight; • Apply sealant below the plates in stud walls, between the bottom of gypsum board sheets and the structure behind, around all penetrations for services and, in general, wherever there is a crack, a hole or the possibility of one developing; • Include sound-absorbing material inside the wall if not already required. The reduction of air leakage is also addressed to some extent by the smoke tightness requirements in the Code. The NRC report entitled “Best Practice Guide on Fire Stops and Fire Blocks and their Impact on Sound Transmission,” provides additional information regarding the possible impacts of fire protection measures on sound transmission. The calculation of and laboratory testing for STC and ASTC ratings are performed on intact assemblies having no penetrations or doors. When measuring ASTC ratings in the field, openings can be blocked with insulation and drywall. To verify that the required acoustical performance is being achieved, a field test can be done at an early stage in the construction; ASTM E336, “Standard Test Method for Measurement of Airborne Sound Attenuation Between Rooms in Appendix A • Volume 2 Page 207 Buildings” gives a complete measurement. A simpler and less expensive method is presented in ASTM E597, “Practice for Determining a Single Number Rating of Airborne Sound Insulation for Use in Multi-Unit Building Specifications”. The rating derived from this test is usually within 2 points of the STC obtained from ASTM E336. It is useful for verifying performance and finding problems during construction. Alterations can then be made prior to project completion. Impact Noise Section 9.11. has no requirements for control of impact noise transmission. Footstep and other impacts can cause severe annoyance in multi-family residences. Builders concerned about quality and reducing occupant complaints will ensure that floors are designed to minimize impact transmission. A recommended criterion is that bare floors (tested without a carpet) should achieve an impact insulation class (IIC) of 55. Some lightweight floors that satisfy this requirement may still cause complaints about low frequency impact noise transmission. Adding carpet to a floor will always increase the IIC rating but will not necessarily reduce low frequency noise transmission. Good footstep noise rejection requires fairly heavy floor slabs or floating floors. Most frequently used methods of test for impact noise are ASTM E492, “Standard Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using The Tapping Machine”, or ASTM E1007, “Standard Test Method for Field Measurement of Tapping Machine Impact Sound Transmission Through Floor- Ceiling Assemblies and Associated Support Structures”. Machinery Noise Elevators, garbage chutes, plumbing, fans, and heat pumps are common sources of noise in buildings. To reduce annoyance from these, they should be placed as far as possible from sensitive areas. Vibrating parts should be isolated from the building structure using resilient materials such as neoprene or rubber.

Tables 1 and 2 of MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” present separating assemblies that comply with Subsection 9.11. However, selecting an appropriate separating assembly is only one part of the solution for reducing airborne sound transmission between adjoining spaces. To fully address the sound performance of the whole system, flanking assemblies must be connected to the separating assembly in accordance with Article 9.11.1.4.

Tables A-9.11.1.4.-A to A-9.11.1.4.-D present generic options for the design and construction of junctions between separating and flanking assemblies. Constructing according to these options is likely to meet or exceed an ASTC rating of 47. Other designs may be equally acceptable if their sound resistance can be demonstrated to meet the minimum ASTC rating or better on the basis of tests referred to in Article 9.11.1.2., or if they comply with Subsection 5.8.1. However, some caution should be applied when designing solutions that go beyond the options provided in these Tables: for example, adding more material to a wall could negatively impact its sound performance or have no effect at all. Table A-9.11.1.4.-A presents compliance options for the construction of separating wall assemblies with flanking floor, ceiling and wall assemblies in horizontally adjoining spaces. Table A-9.11.1.4.-B presents options for improving the sound performance of separating wall systems beyond that achieved by implementing the options presented in Table A-9.11.1.4.-A. The suggested performance improvement options are listed in order of approximate acoustic priority and are interdependent, i.e., if options at the top of the list are not implemented, then options at the bottom of the list will have much lesser effect. Table A-9.11.1.4.-C presents compliance options for the construction of separating floor/ceiling assemblies with flanking wall assemblies in vertically adjoining spaces. Table A-9.11.1.4.-D presents options for improving the sound performance of separating floor/ceiling assemblies beyond that achieved by implementing the options presented in Table A-9.11.1.4.-C. The suggested performance improvement options are listed in order of approximate acoustic priority and are interdependent, i.e., if options at the top of the list are not implemented, then options at the bottom of the list will have much lesser effect. Page 208 Appendix A • Volume 2 Table A-9.11.1.4.-A Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Wall Assemblies in Horizontally Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Wall Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address Assembly with STC ≥ 50 Horizontal Sound Transmission Paths from Table 1 of MMAH Bottom Junction Top Junction Side Junctions Supplementary Standard (between separating wall and (between separating wall and (between separating wall and SB-3 flanking floors) flanking ceiling) flanking walls) • for additional material layer • ceiling is framed with wood • gypsum board on flanking walls and finished flooring, see joists, wood I-joists, or wood ends or is cut at separating wall Table 9.11.1.4. trusses, with or without and is fastened directly to absorptive material(2) in cavities framing or on resilient metal • subfloor on both sides of wall is channels(3) plywood, OSB, waferboard • ceiling joists or trusses are (15.5 mm thick) or tongue and oriented perpendicular to • flanking wall is framed with groove lumber (≥ 17 mm thick) separating wall but are not single row of wood studs, continuous across junction staggered studs on a single • floor is framed with wood joists, (loadbearing case) or parallel to 38 mm x 140 mm plate, or 2 wood I-joists or wood trusses junction (non-loadbearing case) rows of 38 mm x 89 mm wood spaced ≥ 406 mm o.c., with or studs on separate 38 mm x without absorptive material(2) in • gypsum board ceiling is 89 mm plates, with or without cavities fastened directly to bottom of absorptive material(2) in cavities ceiling framing or on resilient • floor joists or trusses are metal channels(3) • flanking wall framing is oriented parallel to separating structurally connected to wall (non-loadbearing case) or separating wall and terminates perpendicular to separating where it butts against framing wall but are not continuous of separating wall or is across junction (loadbearing continuous across junction case) W4, W5, W6 (single stud) W8, W9, W10, W11, W12 Example Showing Side View of Bottom and Top Junctions Example Showing Plan View of (staggered studs) Side Junctions Appendix A • Volume 2 Page 209 Table A-9.11.1.4.-A (Cont’d) Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Wall Assemblies in Horizontally Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Wall Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address Assembly with STC ≥ 50 Horizontal Sound Transmission Paths from Table 1 of MMAH Bottom Junction Top Junction Side Junctions Supplementary Standard (between separating wall and (between separating wall and (between separating wall and SB-3 flanking floors) flanking ceiling) flanking walls) Example Showing Side View of Bottom and Top Junctions Example Showing Plan View of Side Junctions W4, W5, W6 (single stud) W8, W9, W10, W11, W12 (staggered studs) • for additional material layer • wood joists, wood I-joists or • flanking wall framing is and finished flooring, see wood trusses are oriented fastened to adjacent leaf of Table 9.11.1.4. perpendicular or parallel to separating wall • subfloor on both sides of wall separating wall, with or • flanking wall is framed with is plywood, OSB, waferboard without absorptive material(2) single row of wood studs, (15.5 mm thick) or tongue and in cavities staggered studs on a single groove lumber (≥ 17 mm thick) • joist framing at junction is 38 mm x 140 mm plate, or 2 • floor is framed with wood supported on near leaf of rows of 38 mm x 89 mm wood joists, wood I-joists or wood separating wall studs on separate 38 mm x trusses spaced ≥ 400 mm • gypsum board ceiling panels 89 mm plates, with or without o.c., with or without absorptive end at wall framing and are absorptive material(2) in W13, W14, W15 material(2) in cavities fastened directly to bottom of cavities • floor joists or trusses are ceiling framing or on resilient • gypsum board panels on oriented parallel to separating metal channels(3) flanking walls ends or is cut at wall (non-loadbearing case) or framing of separating wall and perpendicular to separating is fastened on resilient metal wall but are not continuous channels(3) or directly to across junction (loadbearing framing of flanking wall if that case) framing and any sheathing are not continuous across the • near leaf of separating wall is junction supported on “designated” joist Page 210 Appendix A • Volume 2 Table A-9.11.1.4.-A (Cont’d) Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Wall Assemblies in Horizontally Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Wall Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address Assembly with STC ≥ 50 Horizontal Sound Transmission Paths from Table 1 of MMAH Bottom Junction Top Junction Side Junctions Supplementary Standard (between separating wall and (between separating wall and (between separating wall and SB-3 flanking floors) flanking ceiling) flanking walls) Example Showing Side View of Bottom and Top Junctions Example Showing Plan View of Side Junctions W13, W14, W15 Appendix A • Volume 2 Page 211 Table A-9.11.1.4.-A (Cont’d) Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Wall Assemblies in Horizontally Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Wall Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address Assembly with STC ≥ 50 Horizontal Sound Transmission Paths from Table 1 of MMAH Bottom Junction Top Junction Side Junctions Supplementary Standard (between separating wall and (between separating wall and (between separating wall and SB-3 flanking floors) flanking ceiling) flanking walls) • F1 concrete floor assembly • F1 concrete floor assembly • flanking wall framing is from Table 2 with mass per from Table 2 with mass per structurally connected to area not less than 300 kg/m2 area not less than 300 kg/m2 separating wall and terminates (e.g. normal-weight concrete (e.g. normal-weight concrete where it butts against framing with average thickness of with average thickness of of separating wall or is 130 mm) 130 mm) continuous across junction • with or without an additional • with or without gypsum board • gypsum board on flanking material layer or finished ceiling suspended below walls ends or is cut at flooring concrete floor separating wall and is fastened directly to framing or on resilient metal channels(3) • flanking wall consists of steel framing (loadbearing or non- loadbearing steel studs) or concrete blocks with mass per area not less than 200 kg/m2 (e.g. normal-weight hollow core concrete block units(4) with a gypsum board lining supported on framing providing a cavity not less than 50 mm deep) S1 to S15 • with or without absorptive material(2) in cavities behind gypsum board of flanking walls Example Showing Side View of Bottom and Top Junctions Example Showing Plan View of Side Junctions Page 212 Appendix A • Volume 2 Table A-9.11.1.4.-A (Cont’d) Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Wall Assemblies in Horizontally Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Wall Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address Assembly with STC ≥ 50 Horizontal Sound Transmission Paths from Table 1 of MMAH Bottom Junction Top Junction Side Junctions Supplementary Standard (between separating wall and (between separating wall and (between separating wall and SB-3 flanking floors) flanking ceiling) flanking walls) • same options as stated above • same options as stated above • same options as stated above for walls S1 to S15 for walls S1 to S15 for walls S1 to S15 • junction at top of concrete block assembly is loadbearing or non-loadbearing resilient joint Example Showing Side View of Bottom and Top Junctions Examples Showing Plan View of Side Junctions B1 to B10 Notes to Table A-9.11.1.4.-A: (1) See also Table A-9.11.1.4.-B. (2) Sound absorptive material is porous (closed-cell foam was not tested) and includes fibre processed from rock, slag, glass or cellulose fibre with a maximum density of 32 kg/m3. See Notes (5) and (8) of Table 1 and Note (5) of Table 2 of MMAH Supplementary Standard SB- 3, “Fire and Sound Resistance Tables” for additional information. (3) Resilient metal channels are formed from steel having a maximum thickness of 0.46 mm (25 gauge) with slits or holes in the single “leg” between the faces fastened to the framing and to the gypsum board (see Figure 4 in MMAH Supplementary Standard SB-3). ASTM C754, “Standard Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products”, describes the installation of resilient metal channels. (4) Normal-weight concrete block units conforming to CSA A165.1, “Concrete block masonry units”, have aggregate with a density not less than 2 000 kg/m3; 190 mm hollow core units are 53% solid, providing a wall mass per area over 200 kg/m 2; 140 mm hollow core units are 75% solid, providing a wall mass per area over 200 kg/m2. Appendix A • Volume 2 Page 213 Table A-9.11.1.4.-B Options for the Construction of a Separating Wall System to Further Improve the Sound Insulation Performance Achieved with the Options in Table A-9.11.1.4.-A Type of Separating Wall Assembly with STC ≥ 50 from Performance Improvement Options for Junctions Between Separating Walls and Table 1 of MMAH Flanking Floor/Ceiling Assemblies • Increase mass per area of additional material layer and finished flooring over subfloor (e.g. concrete or gypsum concrete topping) • Choose separating wall assembly with higher STC rating W4, W5, W6, W8, W9, • Orient floor and ceiling joists parallel to separating wall (non-loadbearing case) W10, W11, W12 • Add resilient layer under additional material layer over subfloor or between additional material layer and finished flooring • Support gypsum board panels of ceiling on resilient metal channels (1) • Support gypsum board panels of flanking walls on resilient metal channels(1) • If seismic or other structural requirements permit, choose a fire block detail at floor/wall junction in accordance with Subsection 9.10.16. that does not provide a rigid connection between the two rows of framing of the separating wall (e.g. subfloor not continuous across junction and semi-rigid fibre insulation board filling the gap in accordance with Article 9.10.16.3.). In this case, an additional material layer would not be necessary. Also, choose separating wall assembly with higher STC rating (e.g. more absorptive material(2) in cavities and/or more gypsum board). • If having a rigid structural connection at the floor/wall junction (such as subfloor continuous across the junction) is required for seismic or other structural reasons, obtain a higher ASTC rating as follows: W13, W14, W15 • Increase combined mass per area of additional material layer over subfloor and finished flooring (e.g. concrete or gypsum concrete topping) • Choose separating wall assembly with higher STC rating (e.g. more absorptive material (2) and/or more gypsum board) • Support gypsum board panels of ceiling on resilient metal channels(1) • Support gypsum board panels of flanking walls on resilient metal channels(1) • Add resilient layer under additional material layer over subfloor or between additional material layer and finished flooring • Choose separating wall assembly with higher STC rating • Increase thickness of concrete floor slab and/or add material layer and finished flooring over subfloor • Add gypsum board ceiling on framing supported under the floor above, with cavity not less than S1 to S15 100 mm deep • Add resilient layer under additional material layer over subfloor or between additional material layer and finished flooring • Support gypsum board panels of flanking walls on resilient metal channels(1) if steel studs are loadbearing type Page 214 Appendix A • Volume 2 Table A-9.11.1.4.-B (Cont’d) Options for the Construction of a Separating Wall System to Further Improve the Sound Insulation Performance Achieved with the Options in Table A-9.11.1.4.-A Type of Separating Wall Assembly with STC ≥ 50 from Performance Improvement Options for Junctions Between Separating Walls and Table 1 of MMAH Flanking Floor/Ceiling Assemblies • Choose separating wall assembly with higher STC rating • Add gypsum board ceiling supported below concrete floor with cavity not less than 100 mm deep and sound absorptive material(2) in cavity • Increase thickness of concrete floor slab and/or add material layer and finished flooring over subfloor B1 to B10 • Add resilient layer under additional material layer over subfloor or between additional material layer and finished flooring and increase mass per area of additional material layer and finished flooring (e.g. floating concrete or gypsum concrete topping) • Support gypsum board panels of flanking walls on resilient metal channels(1) if steel studs are loadbearing type Notes to Table A-9.11.1.4.-B: (1) Resilient metal channels are formed from steel having a maximum thickness of 0.46 mm (25 gauge) with slits or holes in the single “leg” between the faces fastened to the framing and to the gypsum board (see Figure 4 in MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” for additional information.) ASTM C754, “Standard Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products”, describes the installation of resilient metal channels. (2) Sound absorptive material is porous (closed-cell foam was not tested) and includes fibre processed from rock, slag, glass or cellulose fibre with a maximum density of 32 kg/m3. See Notes (5) and (8) of Table 1 and Note (5) of Table 2 of MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” for additional information. Appendix A • Volume 2 Page 215 Table A-9.11.1.4.-C Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Floor/Ceiling Assemblies in Vertically Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Floor/Ceiling Assembly with Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address STC ≥ 50 from Table 2 of Vertical Sound Transmission Paths MMAH Supplementary Standard SB-3 Junctions with Flanking Steel-Framed Walls Junctions with Flanking Concrete Walls • floor ends at flanking wall assembly (T-junction) • floor ends at flanking wall assembly (T-junction) or extends beyond it (cross-junction) or extends beyond it (cross-junction) • steel framing of flanking walls is loadbearing or • one wythe of concrete blocks with mass per area non-loadbearing, with a single row of steel studs, not less than 200 kg/m2 (e.g. normal-weight staggered studs, or 2 rows of studs, with studs hollow core concrete block units(4)) spaced not less than 406 mm o.c., with or without • loadbearing (solid) or non-loadbearing (resilient) absorptive material(2) in cavities junction between top of flanking concrete block • flanking wall structure is fastened to separating wall and floor structure concrete floor but is not continuous across • gypsum board lining is supported on wood or junction steel framing providing a cavity not less than • gypsum board on flanking walls is not continuous 50 mm deep, with or without absorptive across junction and is fastened directly to wall material(2) in cavities framing or on resilient metal channels(3) • gypsum board on flanking walls is not continuous F1 (with or without gypsum across junction and is fastened directly to wall board ceiling) framing or on resilient metal channels(3) Examples Showing Side View of Junctions Page 216 Appendix A • Volume 2 Table A-9.11.1.4.-C (Cont’d) Options for the Design and Construction of Junctions and Flanking Surfaces Between Separating Floor/Ceiling Assemblies in Vertically Adjoining Spaces for Compliance with Clause 9.11.1.1.(1)(b) Type of Separating Floor/Ceiling Assembly with Options for Design and Construction of Junctions and Flanking Surfaces(1) to Address STC ≥ 50 from Table 2 of Vertical Sound Transmission Paths MMAH Supplementary Standard SB-3 Junctions with Flanking Loadbearing or Non-Loadbearing Walls • wood studs of flanking wall are 38 mm x 89 mm or 38 mm x 140 mm and spaced 400 mm or 600 mm o.c. • flanking wall framing consists of single row of wood studs, staggered studs on a single 38 mm x 140 mm plate, or 2 rows of 38 mm x 89 mm wood studs on separate 38 mm x 89 mm plates, with or without absorptive material(2) in wall cavities • gypsum board on flanking walls ends or is cut near floor framing and is fastened directly to wall framing or supported on resilient metal channels(3) Example Showing Side View of Junctions in Example Showing Side View of Junctions in Flanking Loadbearing Wall Flanking Non-Loadbearing Wall F8 to F38 Notes to Table A-9.11.1.4.-C: (1) See also Table A-9.11.1.4.-D. (2) Sound absorptive material is porous (closed-cell foam was not tested) and includes fibre processed from rock, slag, glass or cellulose fibre with a maximum density of 32 kg/m3. See Notes (5) and (8) of Table 1 and Note (5) of Table 2 of MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” for additional information. (3) Resilient metal channels are formed from steel having a maximum thickness of 0.46 mm (25 gauge) with slits or holes in the single “leg” between the faces fastened to the framing and to the gypsum board (see Figure 4 in MMAH Supplementary Standard SB-3). ASTM C754, “Standard Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products”, describes the installation of resilient metal channels. (4) Normal-weight concrete block units conforming to CSA A165.1, “Concrete block masonry units”, have aggregate with a density not less than 2 000 kg/m3;190 mm hollow core units are 53% solid, providing a wall mass per area over 200 kg/m 2; 140 mm hollow core units are 75% solid, providing a wall mass per area over 200 kg/m2. Appendix A • Volume 2 Page 217 Table A-9.11.1.4.-D Options for the Construction of a Separating Floor System to Further Improve the Sound Insulation Performance Achieved with the Options in Table A-9.11.1.4.-C Type of Separating Floor Assembly with STC ≥ 50 from Performance Improvement Options for Junctions Between Separating Floors Table 2 of MMAH and Flanking Wall Assemblies • Add heavier additional material layer over subfloor and/or resilient layer under additional material layer or between additional material layer and finished flooring F1 (with or without gypsum • Add gypsum board ceiling supported at least 100 mm below concrete floor with minimal structural board ceiling) connection (e.g. ceiling framing supported resiliently) and sound absorptive material(1) in cavity • Support gypsum board of flanking walls of lower room on resilient metal channels(2) (if framed with loadbearing studs) • Add heavier additional material layer over subfloor and/or resilient layer under additional material layer or between additional material layer and finished flooring • Add more/heavier gypsum board to ceiling and increase spacing of resilient metal channels(2) to F8 to F38 600 mm o.c. • Support gypsum board of flanking loadbearing walls of lower room on resilient metal channels (2) • Support gypsum board on flanking non-loadbearing walls of lower room on resilient metal channels(2) Notes to Table A-9.11.1.4.-D: (1) Sound absorptive material is porous (closed-cell foam was not tested) and includes fibre processed from rock, slag, glass or cellulose fibre with a maximum density of 32 kg/m3. See Notes (5) and (8) of Table 1 and Note (5) of Table 2 of MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” for additional information. (2) Resilient metal channels are formed from steel having a maximum thickness of 0.46 mm (25 gauge) with slits or holes in the single “leg” between the faces fastened to the framing and to the gypsum board (see Figure 4 in MMAH Supplementary Standard SB-3). ASTM C754, “Standard Specification for Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products”, describes the installation of resilient metal channels. Page 218 Appendix A • Volume 2 A-Table 9.11.1.4. Floor Treatments. The sound insulation performance of lightweight framed floors can be improved by adding floor treatments, i.e., additional layers of material over the subfloor (e.g. concrete topping, OSB or plywood) and finished flooring or coverings (e.g., carpet, engineered wood). Table A-Table 9.11.1.4. presents the mass per area values based on thickness and density of a number of generic floor treatment materials (the values for proprietary products may be different; consult the manufacturer’s current data sheets for their products’ values). Table A-Table 9.11.1.4. Mass per Area of Floor Treatment Materials Floor Treatment Material Thickness, mm Density, kg/m³ Mass per Area, kg/m2 Materials Typically Having a Mass per Area Less than 8 kg/m² Medium-density fibreboard (MDF) 2.9 – 6.1 790 – 810 2.3 – 5.0 12.5 – 13.3 5.6 – 6.6 Plywood – generic softwood 450 – 500 15.5 – 16.3 7.0 – 8.1 Ceramic tile 8.4 700 – 1 000 5.9 – 8.4 Materials Typically Having a Mass per Area Greater than 8 kg/m² but Less than 16 kg/m² Particleboard 11.3 – 19.2 710 – 755 8.1 – 14.5 Medium-density fibreboard (MDF) 13.9 – 21.1 640 – 755 8.9 – 15.9 14.3 – 15.8 8.6 – 10.7 Oriented strandboard (OSB) 600 – 680 17.3 – 18.8 10.4 – 12.8 Plywood – generic softwood 25.5 450 – 500 11.5 – 13.1 Materials Typically Having a Mass per Area Greater than 16 kg/m² but Less than 32 kg/m² Medium-density fibreboard (MDF) 25.0 – 32.1 640 – 740 16.0 – 23.7 Materials Typically Having a Mass per Area Greater than 32 kg/m² Concrete 40.0 – 50.0 2 015 – 2 380 80.6 – 119.0 Gypsum concrete 25.0 1 840 – 1 870 46.1 – 46.7 Column 1 2 3 4 Appendix A • Volume 2 Page 219 A-Table 9.12.2.2. Minimum Depths of Foundations. The requirements for clay soils or soils not clearly defined are intended to apply to those soils that are subject to significant volume changes with changes in moisture content.

Figure A-9.12.2.2.(2) Foundation Insulation and Heat Flow to Footings Page 220 Appendix A • Volume 2

The deleterious debris referred to in this provision includes, but is not limited to: • organic material and other material subject to decomposition and compaction, which could have an adverse effect on grading around the building, • materials that will off-gas and have the potential to pose a health hazard, and • materials that are incompatible with materials used in the foundations, footings, drainage materials or components, or other elements of the building whose required performance would be adversely affected.

Excess water from cast-in-place concrete and ground moisture tends to migrate toward interior spaces, particularly in the spring and summer. Where moisture-susceptible materials, such as finishes or wood members, are in contact with the foundation wall, the moisture needs to be controlled by installing a moisture barrier on the interior surface of the foundation wall that extends from the underside of the interior finish up the face of the wall to a point just above the level of the ground outside. The reason the moisture barrier on the interior surface of the foundation wall must be terminated near ground level is to allow any moisture that finds its way into the finished wall cavity from the interior space (through leaks in the air or vapour barrier) to diffuse to the exterior. If the vapour permeance of dampproofing membranes or coatings exceeds 170 ng/(Pa·s·m2), such moisture barriers may be carried full height; if their vapour permeance is less than that, this moisture risks being trapped on the interior surface of the moisture barriers. The permeance limit corresponds to the lower limit for breather-type membranes, such as asphalt-impregnated sheathing paper. Some insulation products can also be used to protect interior finishes from the effects of moisture. They have shown acceptable performance when applied over the entire foundation wall because, in this case, they also provide vapour barrier and moisture barrier functions and possibly also the air barrier function. Where a single product provides all these functions, there is no risk of trapping moisture between two functional barriers with low water vapour permeance.

Finishing a concrete slab placed directly on polyethylene can, in many cases, cause problems for the inexperienced finisher. A rule of finishing, whether concrete is placed on polyethylene or not, is to never finish or “work” the surface of the slab while bleed water is present or before all the bleed water has risen to the surface and evaporated. If finishing operations are performed too early, such as before all the bleed water has risen and evaporated, surface defects such as blisters, crazing, scaling and dusting can result. This is often the case with slabs placed directly on polyethylene. The amount of bleed water that may come to the surface and the time required for this to happen is increased from that of a slab placed on a compacted granular base. The excess water in the mix from the bottom portion of the slab cannot bleed downward and out of the slab and be absorbed into the granular material below, because of the polyethylene. Therefore, all bleed water, including that from the bottom of the slab, must now rise through the slab to the surface. Quite often in such cases, finishing operations are begun too soon and surface defects result. One solution that is often suggested is to place a layer of sand between the polyethylene and the concrete. However, this is not an acceptable solution for the following reason: it is unlikely that the polyethylene will survive the slab pouring process entirely intact. Nevertheless, the polyethylene will still be effective in retarding the flow of soil gas if it is in intimate contact with the concrete; soil gas will only be able to penetrate where a break in the polyethylene coincides with a crack in the concrete. The majority of concrete cracks will probably be underlain by intact polyethylene. On the other hand, if there is an intervening layer of a porous medium, such as sand, soil gas will be able to travel laterally from a break in the polyethylene to the nearest crack in the concrete and the total system will be much less resistant to soil gas penetration. To reduce and/or control the cracking of concrete slabs, it is necessary to understand the nature and causes of volume changes of concrete and in particular those relating to drying shrinkage. The total amount of water in a mix is by far the largest contributor to the amount of drying shrinkage and resulting potential cracking that may be expected from a given concrete. The less total amount of water in the mix, the less volume change (due to evaporation of water), which means the less drying shrinkage that will occur. To lessen the volume change and potential cracking due to drying shrinkage, a mix with the lowest total amount of water that is practicable should always be used. To lower the water content of a mix, superplasticizers are often used to provide the needed workability of the concrete during the placing operation. High water/cementing materials Appendix A • Volume 2 Page 221 ratio concretes usually have high water content mixes. They should be avoided to minimize drying shrinkage and cracking of the slab. The water/cementing materials ratio for slabs-on-ground should be no higher than 0.55.

Outdoor air entering a dwelling through above-grade leaks in the building envelope normally improves the indoor air quality in the dwelling by reducing the concentrations of pollutants and water vapour. It is only undesirable because it cannot be controlled. On the other hand, air entering a dwelling through below-grade leaks in the envelope may increase the water vapour content of the indoor air and may also bring in a number of pollutants which it picks up from the soil. This mixture of air, water vapour and pollutants is sometimes referred to as “soil gas”. One pollutant often found in soil gas is radon. Sentence 9.13.4.2.(1), which requires the installation of an air barrier system, addresses the protection from all soil gases, while the remainder of Article 9.13.4.2. along with Article 9.13.4.3., which require the provision of the means to depressurize the space between the air barrier and the ground, specifically address the capability to mitigate high radon concentrations in the future, should this become necessary. Radon is a colourless, odourless, radioactive gas that occurs naturally as a result of the decay of radium. It is found to varying degrees as a component of soil gas in all regions of Canada and is known to enter dwelling units by infiltration into basements and crawl spaces. The presence of the decay products of radon in sufficient quantity can lead to increased risk of lung cancer. The potential for high levels of radon infiltration is very difficult to evaluate prior to construction and thus a radon problem may only become apparent once the building is completed and occupied. MMAH Supplementary Standard SB-9 requires the application of certain radon exclusion measures in dwellings where methane or radon gasses are known to be a problem. The principal method of resisting the ingress of all soil gases, a resistance which is required for all buildings (see Sentence 9.13.4.2.(1)), is to seal the interface between the soil and the occupied space, so far as is reasonably practicable. Sections 9.18. and 9.25. contain requirements for air and soil gas barriers in assemblies in contact with ground, including those in crawl spaces. Providing control joints to reduce cracking of foundation walls and airtight covers for sump pits (see Section 9.14.) are other measures that can help achieve this objective. The requirements provided in Subsection 9.25.3. are explained in Appendix Notes A-9.25.3.4. and 9.25.3.6. and A-9.25.3.6.(2) and (3). The principal method of excluding radon is to ensure that the pressure difference across the ground space interface is positive (i.e., towards the outside) so that the inward flow of radon through any remaining leaks will be minimized. The requirements provided in Article 9.13.4.3. are explained in Appendix Note A-9.13.4.3.

The criterion used by Health Canada to establish the guideline for acceptable radon concentration is the time that occupants spend inside buildings. Health Canada recommends installing a means for the future removal of radon in buildings that are occupied by persons for more than 4 hours per day. Sentence 9.13.4.2.(3) may therefore not apply to buildings or portions of buildings that are intended to be occupied for less than 4 hours a day. Addressing a radon problem in such buildings in the future, should that become necessary, can also be achieved by providing a means for increased ventilation at times when these buildings are occupied.

Providing Performance Criteria for the Depressurization of the Space Between the Air Barrier and the Ground Article 9.13.4.3. contains two sets of requirements: Sentence (2) describes the criteria for subfloor depressurization systems using performance-oriented language, while Sentence (3) describes one particular acceptable solution using more prescriptive language. In some cases, subfloor depressurization requires a solution other than the one described in Sentence (3), for example, where compactable fill is installed under slab-on-grade construction. Page 222 Appendix A • Volume 2 Completion of a Subfloor Depressurization System The completion of a subfloor depressurization system may be necessary to reduce the radon concentration to a level below the guideline specified by Health Canada. Further information on protection from radon ingress can be found in the following Health Canada publications: • “Radon: A Guide for Canadian Homeowners” (CMHC/HC), and • “Guide for Radon Measurements in Residential Dwellings (Homes).”

To allow effective depressurization of the space between the air barrier and the ground, the extraction opening (the pipe) should not be blocked and should be arranged such that air can be extracted from the entire space between the air barrier and the ground. This will ensure that the extraction system can maintain negative pressure underneath the entire floor (or in heated crawl spaces underneath the air barrier). The arrangement and location of the extraction system inlet(s) may have design implications where the footing layout separates part of the space underneath the floor. Figure A-9.13.4.3.(2)(b) and (3)(b)(i) Acceptable Configurations for the Extraction Opening in a Depressurization System Appendix A • Volume 2 Page 223

In addition to the prevention of heat loss, some types of mineral fibre insulation, such as rigid glass fibre, are installed on the exterior of basement walls for the purpose of moisture control. This is sometimes used instead of crushed rock as a drainage layer between the basement wall and the surrounding soil in order to facilitate the drainage of soil moisture. Water drained by this drainage layer must be carried away from the foundation by the footing drains or the granular drainage layer in order to prevent it from developing hydro-static pressure against the wall. Provision must be made to permit the drainage of this water either by extending the insulation or crushed rock to the drain or by the installation of granular material connecting the two. The installation of such drainage layer does not eliminate the need for normal waterproofing or dampproofing of walls as specified in Section 9.13.

Similar Structures. Decks, balconies, verandas and similar platforms that are attached to a building or that have an area greater than 10 m 2 are, by definition, considered as buildings or parts of buildings. Consequently, they are subject to the requirements in Section 9.15.

Insulating concrete form (ICF) walls are concrete walls that are cast into polystyrene forms, which remain in place after the concrete has cured. Flat ICF walls are solid ICF walls where the concrete is of uniform thickness over the height and width of the wall.

Tabular data and figures in CSA S406, “Specification of permanent wood foundations for housing and small buildings,” are based upon the general principles provided in CSA O86, “Engineering design in wood” with the following assumptions: • soil bearing capacity: 75 kPa or more, • clear spans for floors: 5 m or less, • floor loadings: 1.9 kPa for first floor and suspended floor, and 1.4 kPa for second storey floor, • foundation wall heights: 2.4 for slab floor foundation, 3.0 m for suspended wood floor foundation, • top of granular layer to top of suspended wood floor: 600 mm, • lateral load from soil pressure: equivalent to fluid pressure of 4.7 kPa per metre of depth, • ground snow load: 3 kPa, • basic snow load coefficient: 0.6, • roof loads are carried to the exterior wall, • dead loads: roof 0.50 kPa floor 0.47 kPa wall (with siding) 0.32 kPa wall (with masonry veneer) 1.94 kPa foundation wall 0.27 kPa partitions 0.20 kPa

The footing sizes in Table 9.15.3.4. are based on typical construction consisting of a roof, not more than 3 storeys, and centre bearing walls or beams. For this reason, Clause 9.15.3.3.(1)(b) stipulates a maximum supported joist span of 4.9 m. It has become common to use flat wood trusses or wood I-joists to span greater distances in floors of small buildings. Where these spans exceed 4.9 m, minimum footing sizes may be based on the following method: (a) Determine for each storey the span of joists that will be supported on a given footing. Sum these lengths (sum 1). (b) Determine the product of the number of storeys times 4.9 m (sum 2). (c) Determine the ratio of sum1, to sum2. (d) Multiply this ratio by the minimum footing sizes in Table 9.15.3.4. to get the required minimum footing size. Page 224 Appendix A • Volume 2 Example: A 2-storey house is built using wood I-joists spanning 6 m. (a) sum1 = 6 + 6 = 12 m (b) sum2 = 4.9 x 2 = 9.8 m (c) ratio suml/sum2 = 12/9.8 = 1.22 (d) required minimum footing size = 1.22 x 350 mm (minimum footing size provided in Table 9.15.3.4.) = 427 mm. A-Table 9.15.4.2.-A Flat Insulating Concrete Form Walls as Foundation Walls. Article 9.15.4.2. allows insulating concrete forms (ICFs) to be used to form both laterally supported and laterally unsupported flat, plain (unreinforced) concrete foundation walls intended to support wood-frame walls, floors and roofs under the conditions stipulated in Table 9.15.4.2.-A. Where the limits stated in the Table are exceeded, or where the ICF foundation wall is intended to support one or two storeys of concrete walls formed with flat wall ICFs above ground, Article 9.15.4.5. applies.

Depressions and ridges often develop at the soil surface or granular base from construction activity prior to the placement of a concrete slab. Allowances for such irregularities in the base must be recognized. A maximum tolerance of -10 mm is permitted provided the minimum slab thickness at any point is not less than 65 mm and the mean thickness of the concrete slab (exclusive of topping) is 75 mm, as shown in Figure A-9.16.4.3.(1). Figure A-9.16.4.3.(1) Mean Thickness of Concrete Slabs

Because the Building Code does not provide prescriptive criteria to describe the minimum required lateral support, structures are limited to those that have demonstrated effective performance over time and those that are designed according to Part 4. Verandas on early 20th century homes provide one example of structures whose floor and roof are typically tied to the rest of the building to provide effective lateral support. Large decks set on tall columns, however, are likely to require additional lateral support even where they are connected to the building on one side.

The permitted live floor loads of 2.4 kPa and the spans described for steel beams, wood beams and floor joists are such that the load on columns could exceed 36 kN, the maximum allowable load on columns prescribed in CAN/CGSB-7.2, “Adjustable Steel Columns”. In the context of Part 9, loads on columns are calculated from the supported area times the live load per unit area, using the supported length of joists and beams. The supported length is half of the joist spans on each side of the beam and half the beam span on each side of the column. Dead load is not included based on the assumption that the maximum live load will not be applied over the whole floor. Designs according to Part 4 must consider all applied loads. Appendix A • Volume 2 Page 225

The purpose of the requirement is to protect combustible ground cover from smoldering cigarette butts that may drop through air registers. The protective material should extend beyond the opening of the register and have up-turned edges, as a butt may be deflected sideways as it falls.

Controlling the flow of moisture by air leakage and vapour diffusion into roof and attic spaces is necessary to limit moisture- induced deterioration. Given that imperfections normally exist in the vapour barriers and air barrier systems, recent research indicates that venting of roof and attic spaces is generally still required. The exception provided in Article 9.19.1.1. recognizes that some specialized ceiling-roof assemblies, such as those used in some factory-built buildings, have, over time, demonstrated that their construction is sufficiently tight to prevent excessive moisture accumulation. In these cases, ventilation would not be required.

The term “open space” refers to the space between the insulation and the roof sheathing. Sentence 9.19.2.1.(1) requires the installation of an access hatch where the open space in the attic or roof is large enough to allow visual inspection. Although the dimensions of an uninsulated attic or roof space may meet the size that triggers the requirement for an access hatch to be installed, most of that space will actually be filled with insulation and may therefore not be easily inspected, particularly in smaller buildings or under low-sloped roofs.

The dimensions for attic access as provided for in the Building Code are minimum dimensions. Where a fuel fired appliance is to be located in the attic, a larger attic access opening shall be provided in conformance with the Gas Utilization Code or other applicable installation code.

Information on seismic zones for various localities can be found in MMAH Supplementary Standard SB-1.

Masonry veneer must be supported on a stable structure in order to avoid cracking of the masonry due to differential movement relative to parts of the support. Wood framing is not normally used as a support for the weight of masonry veneer because of its shrinkage characteristics. Where the weight of masonry veneer is supported on a wood structure, as is the case for the preserved wood foundations referred to in Sentence 9.20.5.1.(1) for example, measures must be taken to ensure that any differential movement that may be harmful to the performance of masonry is minimized or accommodated. The general principle stated in Article 9.4.1.1., however, makes it possible to support the weight of masonry veneer on wood framing, provided that engineering design principles prescribed in Part 4 are followed to ensure that the rigidity of the support is compatible with the stiffness of the masonry being supported and that differential movements between the support and masonry are accommodated. A-Table 9.20.5.2.-C Steel Beams Supporting Masonry Veneer. Design Assumptions 1. Density of Veneer: • Brick = 18.9 kN/m3 • Limestone or Sandstone = 22.62 kN/m3 2. Dead Load of Veneer: • 70 mm Brick = 0.070 x 18.9 = 1.32 kPa • 89 mm Brick = 0.089 x 18.9 = 1.68 kPa • 100 mm Stone = 0.10 x 22.62 = 2.26 kPa Page 226 Appendix A • Volume 2 3. Design Standards: • CSA S304.1-94, “Masonry Design for Buildings (Limit States Design)” • CSA S16.1-94, “Limit States Design of Steel Structures” 4. Design Assumptions - Steel Angles in Table 9.20.5.2.-B: • For angle sizes (150 x 90 x 10; 150 x 90 x 13; 150 x 100 x 13; 180 x 100 x 10; 180 x 100 x 13) • Mid-span deflection limited to span/700 as per Note (6) of Table 9.20.5.2.-A in the Building Code. • Arch action of the brick veneer is assumed, which means that all brick weight within a 45 degree angle of the edge of the opening is not considered in the design of the lintel. • The steel yield strength is 300 MPa. 5. Design Assumptions - Steel Wide Flange Beams in Table 9.20.5.2.-C: • Mid-span deflection limited to span/700 as per Note (6) of Table 9.20.5.2.-A in the Building Code for the brick load only. • Mid-span deflection limited to span/600 as per Clause 6.3.5.1 of CSA S304.1 for brick weight plus roof live load (see below). • Arch action of the brick veneer is assumed, which means that all brick weight within a 45 degree angle of the edge of the opening is not considered in the design of the lintel. • The beam is designed for a roof live load of 2.3 kN/m. This is to account for the fact that the steel beam will typically support a wood stud wall and a gable truss or outlook rafters as well as the brick veneer. • The beam is considered to be laterally unsupported along its length since it does not support a floor. • The beam is supported by steel columns at each end. • The steel yield strength is 300 MPa.

Figure A-9.20.8.5.(1) Maximum Projection of Masonry Veneer Beyond its Support Appendix A • Volume 2 Page 227

Figure A-9.20.12.2.(2) Maximum Corbel Dimensions

The reason for installing sheathing paper behind masonry walls is to prevent rainwater from reaching the interior finish if it should leak past the masonry. The sheathing paper intercepts the rainwater and leads it to the bottom of the wall where the flashing directs it to the exterior via weep holes. If the insulation is a type that effectively resists the penetration of water and is installed so that water will not collect behind it, then there is no need for sheathing paper. If water that runs down between the masonry and the insulation is able to leak out at the joints in the insulation, such insulation will not act as a substitute for sheathing paper. If water cannot leak through the joints in the insulation but collects in cavities between the masonry and insulation, subsequent freezing could damage the wall. Where sheathing paper is not used, therefore, the adhesive or mortar should be applied to form a continuous bond between the masonry and the insulation. If this is not practicable because of an irregular masonry surface, then sheathing paper is necessary.

Certain solid-fuel burning appliances may be connected to factory-built chimneys other than those specified in Sentence 9.21.1.3.(1) if tests show that the use of such a chimney will provide an equivalent level of safety, as an alternative solution pursuant to Section 2.1. of Division C.

Masonry chimneys with metal liners may be permitted to serve solid-fuel burning appliances if tests show that such liners will provide an equivalent level of safety, as an alternative solution pursuant to Section 2.1. of Division C. Page 228 Appendix A • Volume 2

Figure A-9.21.4.4.(1) Vertical and Horizontal Distance from Chimney Top to Roof

Where a chimney is fastened to the house framing with metal anchors, in accordance with CAN/CSA-A370, “Connectors for Masonry”, it is considered to have adequate lateral support. The portion of the chimney stack above the roof is considered as free standing and may require additional lateral support.

For purposes of this Sentence, an exterior chimney can be considered to be one which has at least one surface exposed to the outside atmosphere or unheated space over the majority of its height. All other chimneys should be considered to be interior.

The prescriptive requirements in Section 9.23. apply only to standard light wood-frame construction. Other structural framing systems, such as post, beam and plank construction, plank frame wall construction, and log construction must be designed in accordance with Part 4.

In previous editions of the Code, Sentence 9.23.1.1.(1) referred to “conventional” wood-frame construction. Over time, conventions have changed and the application of Part 9 has expanded. The prescriptive requirements provided in Section 9.23. still focus on lumber beams, joists, studs and rafters as the main structural elements of “wood-frame construction”. The requirements recognize - and have recognized for some time - that walls and floors may be supported by components made of material other than lumber; for example, by foundations described in Section 9.15. or by steel beams described in Article 9.23.4.3. These components still fall within the general category of wood-frame construction. With more recent innovations, alternative structural components are being incorporated into wood-frame buildings. Wood I-joists, for example, are very common. Where these components are used in lieu of lumber, the requirements in Section 9.23. that specifically apply to lumber joists do not apply to these components: for example, limits on spans and acceptable locations for notches and holes. However, requirements regarding the fastening of floor sheathing to floor joists still apply, and the use of wood I-joists does not affect the requirements for wall or roof framing. Appendix A • Volume 2 Page 229 Similarly, if steel floor joists are used in lieu of lumber joists, the requirements regarding wall or roof framing are not affected. Conversely, Sentence 9.23.1.1.(1) precludes the installation of pre-cast concrete floors on wood-frame walls since these are not “generally comprised of ... small repetitive structural members ... spaced not more than 600 mm o.c." Thus, the reference to “engineered components” in Sentence 9.23.1.1.(1) is intended to indicate that, where an engineered product is used in lieu of lumber for one part of the building, this does not preclude the application of the remainder of Section 9.23. to the structure, provided the limits to application with respect to cladding, sheathing or bracing, spacing of framing members, supported loads and maximum spans are respected.

Interior construction, which includes sill plates, that is not in contact with the ground, but is exposed to occasional sources of moisture, is considered to be a dry interior environment for the purpose of Sentence 9.23.2.4.(3).

Where power nails or nails with smaller diameters than that required by Table 9.23.3.4. are used to connect framing, the following equations can be used to determine the required spacing or required number of nails. The maximum spacing can be reduced using the following equation: Sadj = Stable x (Dred / Dtable)² where Sadj = adjusted nail spacing ≥ 20 × nail diameter, Stable = nail spacing required by Table 9.23.3.4., Dred = smaller nail diameter than that required by Table 9.23.3.1., and Dtable = nail diameter required by Table 9.23.3.1. The number of nails can be increased using the following equation: Nadj = Ntable x (Dtable / Dred)² where Nadj = adjusted number of nails, Ntable = number of nails required by Table 9.23.3.4., Dtable = nail diameter required by Table 9.23.3.1., and Dred = smaller nail diameter than required by Table 9.23.3.1. Note that nails should be spaced sufficiently far apart—preferably no less than 55 mm apart—to avoid splitting of framing lumber.

The requirement that wood screws conform to ANSI/ASME B18.6.1., “Wood Screws (Inch Series)” is not intended to preclude the use of Robertson head screws. The requirement is intended to specify the mechanical properties of the fastener, not to restrict the means of driving the fastener.

The intent of the phrase “staggering the nails in the direction of the grain” is illustrated in Figure A-9.23.3.3.(1). Page 230 Appendix A • Volume 2 Figure A-9.23.3.3.(1) Staggered Nailing A-Table 9.23.3.5.-B Alternative Nail Sizes. Where power nails or nails having a different diameter than the diameters listed in CSA B111, “Wire Nails, Spikes and Staples,” are used to connect the edges of the wall sheathing to the wall framing of wood-sheathed braced wall panels, the maximum spacing should be as shown in A-Table 9.23.3.5.-B. A-Table 9.23.3.5.-B Alternative Nail Diameters and Spacing Nail Diameter, mm(1) Maximum Spacing of Nails Along Edges of Element Wall Sheathing, mm o.c. 2.19 – 2.52 75 2.53 – 2.82 100 Plywood, OSB or waferboard 2.83 – 3.09 125 > 3.09 150 Notes to A-Table 9.23.3.5.-B: (1) For alternative nail lengths of 63 mm or longer.

In these span tables the term “rafter” refers to a sloping wood framing member which supports the roof sheathing and encloses an attic space but does not support a ceiling. The term “roof joist” refers to a horizontal or sloping wood framing member that supports the roof sheathing and the ceiling finish but does not enclose an attic space. Where rafters or roof joists are intended for use in a locality having a higher specified roof snow load than shown in the tables, the maximum member spacing may be calculated as the product of the member spacing and specified snow load shown in the span tables divided by the specified snow load for the locality being considered. The following examples show how this principle can be applied: (a) For a 3.5 kPa specified snow load, use spans for 2.5 kPa and 600 mm o.c. spacing but space members 400 mm o.c. (b) For a 4.0 kPa specified snow load, use spans for 2.0 kPa and 600 mm o.c. spacing but space members 300 mm o.c. The maximum spans in the span tables are measured from the inside face or edge of support to the inside face or edge of support. In the case of sloping roof framing members, the spans are expressed in terms of the horizontal distance between supports rather than the length of the sloping member. The snow loads are also expressed in terms of the horizontal projection of the sloping roof. Spans for odd size lumber may be estimated by straight line interpolation in the tables. These span tables may be used where members support a uniform live load only. Where the members are required to be designed to support a concentrated load, they must be designed in conformance with Subsection 4.3.1. Appendix A • Volume 2 Page 231 Supported joist length in Span Tables 9.23.4.2.-H, 9.23.4.2.-I and 9.23.4.2.-J means half the sum of the joist spans on both sides of the beam. For supported joist lengths between those shown in the tables, straight line interpolation may be used in determining the maximum beam span. Span Tables 9.23.4.2.-A to 9.23.4.2.-L and 9.23.12.3.-A to 9.23.12.3.-D cover only the most common configurations. Especially in the area of floors, a wide variety of other configurations is possible: glued subfloors, concrete toppings, machine stress rated lumber, etc. The Canadian Wood Council publishes “The Span Book”, a compilation of span tables covering many of these alternative configurations. Although these tables have not been subject to the formal committee review process, the Canadian Wood Council generates many of these span tables for wood structural components; thus, Building Code users can be confident that the alternative span tables in “The Span Book” are consistent with these span tables in the Building Code and with relevant Building Code requirements. Spans for wood joists, rafters and beams which fall outside the scope of these tables, including those for U.S. species and individual species not marketed in the commercial species combinations described in the span tables, can be calculated in conformance with CSA O86.1, “Engineering Design in Wood”.

Frame Floors. In addition to the normal strength and deflection analyses, the calculations on which the floor joist span tables are based include a method of ensuring that the spans are not so long that floor vibrations could lead to occupants perceiving the floors as too “bouncy” or “springy”. Limiting deflection under the normal uniformly distributed loads to 1/360 of the span does not provide this assurance. Normally, vibration analysis requires detailed dynamic modelling. However, the calculations for the span tables use the following simplified static analysis method of estimating vibration-acceptable spans: • The span which will result in a 2 mm deflection of a single joist supporting a 1 kN concentrated midpoint load is calculated. • This span is multiplied by a factor, K, to determine the “vibration-controlled” span for the entire floor system. If this span is less than the strength- or deflection-controlled span under uniformly distributed load, the vibration-controlled span becomes the maximum span. • The K factor is determined from the following relationship: ln(K) = A – B • ln(Si/S184) + G where A, B = constants, the values of which are determined from Tables A-9.23.4.2.(2)-A or -B G = constant, the value of which is determined from Table A-9.23.4.2.(2)-C Si = span which results in a 2 mm deflection of the joist in question under a 1 kN concentrated midpoint load S184 = span which results in a 2 mm deflection of a 38 x 184 mm joist of same species and grade as the joist in question under a 1 kN concentrated midpoint load. For a given joist species and grade, the value of K shall not be greater than K 3, the value which results in a vibration- controlled span of exactly 3 m. This means that for vibration-controlled spans 3 m or less, K always equals K3, and for vibration-controlled spans greater than 3 m, K is as calculated. Note that, for a sawn lumber joist, the ratio Si/S184 is equivalent to its depth (mm) divided by 184. Due to rounding differences, the method, as presented here, might produce results slightly different from those produced by the computer program used to generate the span tables. Page 232 Appendix A • Volume 2 Table A-9.23.4.2.(2)-A Constants A and B for Calculating Vibration-Controlled Floor Joist Spans - General Cases Subfloor With Strapping(1) With Bridging With Strapping and Bridging Thickness, Joist Spacing, mm Joist Spacing, mm Joist Spacing, mm mm 300 400 600 300 400 600 300 400 600 Constant A 15.5 0.30 0.25 0.20 0.37 0.31 0.25 0.42 0.35 0.28 19.0 0.36 0.30 0.24 0.45 0.37 0.30 0.50 0.42 0.33 Constant B 0.33 0.38 0.41 Column 1 2 3 4 5 6 7 8 9 10 Notes to Table A-9.23.4.2.(2)-A: (1) Gypsum board attached directly to joists can be considered equivalent to strapping. Table A-9.23.4.2.(2)-B Constants A and B for Calculating Vibration-Controlled Floor Joist Spans - Special Cases Joists with Ceiling Attached to Wood Furring(1) Joists with Concrete Topping(2) Subfloor Without Bridging With Bridging With or Without Bridging Thickness, mm Joist Spacing, mm Joist Spacing, mm Joist Spacing, mm 300 400 600 300 400 600 300 400 600 Constant A 15.5 0.39 0.33 0.24 0.49 0.44 0.38 0.58 0.51 0.41 19.0 0.42 0.36 0.27 0.51 0.46 0.40 0.62 0.56 0.47 Constant B 0.34 0.37 0.35 Column 1 2 3 4 5 6 7 8 9 10 Notes to Table A-9.23.4.2.(2)-B: (1) Wood furring means 19 x 89 mm boards not more than 600 mm o.c., or 19 x 64 mm boards not more than 300 mm o.c. For all other cases, see Table A-9.23.4.2.(2)-A. (2) 30 mm to 51 mm normal weight concrete (not less than 20 MPa) placed directly on the subflooring. Table A-9.23.4.2.(2)-C Constant G for Calculating Vibration-Controlled Floor Joist Spans Floor Description Constant G Floors with nailed(1) subfloor 0.00 Floor with nailed and field-glued(2) subfloor, vibration-controlled span greater than 3 m 0.10 Floor with nailed and field-glued(2) subfloor, vibration-controlled span 3 m or less 0.15 Column 1 2 Notes to Table A-9.23.4.2.(2)-C: (1) Common wire nails, spiral nails or wood screws can be considered equivalent for this purpose. (2) Subfloor field-glued to floor joists with elastomeric adhesive complying with standard CAN/CGSB-71.26-M, “Adhesives for Field-Gluing Plywood to Lumber Framing for Floor Systems”. Appendix A • Volume 2 Page 233 Additional background information on this method can be found in the following publications: • Onysko, D.M. Serviceability Criteria for Residential Floors Based on a Field Study of Consumer Response. Project 03-50-10-008. Forintek Canada Corp., Ottawa, Canada 1985. • Onysko, D.M. Performance Criteria for Residential Floors Based on Consumer Responses. 1988 International Conference on Timber Engineering, Seattle, September 19-22, Forest Products Research Society, Vol.1, 1988, pp. 736-745. • Onysko, D.M. Performance and Acceptability of Wood Floors - Forintek Studies. Proceedings of Symposium/Workshop on Serviceability of Buildings, Ottawa, May 16-18, National Research Council of Canada, Ottawa, 1988. A-Table 9.23.4.3. Spans for Steel Beams. The spans provided in Table 9.23.4.3. reflect a balance of engineering and acceptable proven performance. The spans have been calculated based on the following assumptions: • Simply supported beam spans • Laterally supported top flange • Yield strength 350 MPa • Deflection limit L/360 • Live load = 1.9 kPa • Dead load 1.5 kPa. The calculation used to establish the specified maximum beam spans also applies a revised live load reduction factor to account for the lower probability of a full live load being applied over the supported area in Part 9 buildings.

A beam may be considered to be laterally supported if wood joists bear on its top flange at intervals of 600 mm or less over its entire length, if all the load being applied to this beam is transmitted through the joists and if 19 mm by 38 mm wood strips in contact with the top flange are nailed on both sides of the beam to the bottom of the joists supported. Other additional methods of positive lateral support are acceptable. For supported joist lengths intermediate between those in the table, straight line interpolation may be used in determining the maximum beam span. Design Assumptions for Tables 9.23.4.3.-A to 9.23.4.3.-J (Steel Beams Supporting Roofs and Floors) 1. Density of Brick Veneer: • Brick = 18.9 kN/m3 2. Dead Load of Brick Veneer: • 89 mm Brick = 0.089 x 18.9 = 1.68 kPa • Brick loading on beam = 3 m high brick x 1.68 = 5.04 kN/m. This is based on a single storey wall with windows and a brick gable above the top of the stud wall. In this case, the windows in the exterior wall nullify the arch action of the brick and the load is applied uniformly along the length of the beam. 3. Dead Load of Structure: • Roof = 0.62 kPa (Asphalt shingle roof) • Floor = 1.5 kPa as per Appendix Note A-Table 9.23.4.3. 4. Live Loads: • Floor = 1.9 kPa • Roof = as indicated in the Tables 5. Design Standards: • CSA S304.1-94, “Masonry Design for Buildings (Limit States Design)" • CSA S16.1-94, 'Limit States Design of Steel Structures" Page 234 Appendix A • Volume 2 6. Design Assumptions: • Simply supported beam spans • Laterally supported top flange • Yield strength 300 MPa • Mid-span deflection limited to span/600 as per Clause 6.3.5.1 of CSA S304.1, for brick weight plus live load. The self-weight of structure is typically on the beam prior to the application of the brick so the deflection check need only include live and brick loads. • For siding walls the mid-span deflection is limited to span/360 on live load.

Vibration-controlled spans given in Table 9.23.4.2.-B for concrete topping are based on a partial composite action between the concrete, subflooring and joists. Normal weight concrete having a compressive strength of not less than 20 MPa, placed directly on the subflooring, provides extra stiffness and results in increased capacity. The use of a bond breaker between the topping and the subflooring, or the use of lightweight concrete topping limits the composite effects. Where either a bond breaker or lightweight topping is used, Table 9.23.4.2.-A may be used but the additional dead load imposed by the concrete must be considered. The addition of 51 mm of concrete topping can impose an added load of 0.8 to 1.2 kPa, depending on the density of the concrete. Example: Assumptions: - basic dead load = 0.5 kPa - topping dead load = 0.8 kPa - total dead load = 1.3 kPa - live load = 1.9 kPa - vibration limit: per Note A-9.23.4.2.(2) - deflection limit = 1/360 - ceiling attached directly to joists, no bridging The spacing of joists in the span tables can be conservatively adjusted to allow for the increased load by using the spans in Table 9.23.4.2.-A for 600 mm spacing, but spacing the joists 400 mm apart. Similarly, floor beam span tables can be adjusted by using 4.8 m supported length spans for cases where the supported length equals 3.6 m.

Figure A-9.23.8.3. Joint Location in Built-up Beams Appendix A • Volume 2 Page 235

Design Assumptions for Tables 9.23.10.1.-A to 9.23.10.1.-D: 1. Roof dead load is 0.5 kPa (asphalt shingle roof) as per rafter and lintel tables in the Building Code. 2. Specified roof snow load is the factored load incorporating rain load as per the rafter, header and lintel spans in the Building Code. 3. Wind loads are based on wind loads in the 2006 Building Code and the 2005 edition of the NBC as adopted in the Engineering Guide for Wood Frame Construction published by the Canadian Wood Council a. Basic wind pressure is the 1 in 50 year pressure found in Table 1.2 of MMAH Supplementary Standard SB-1 b. Ce = 0.7 as per Sentence 4.1.7.1.(5)(b) in the Building Code c. CpCg = –2.1 for ultimate limit state for wind acting alone d. CpCg = –1.75 for the serviceability limit state e. CpCg = 1.5 for wind acting in combination with gravity loads f. Cpi varied from –0.45 to 0.3 as per User’s Guide - NBC 2005, Structural Commentaries (Part 4 of Division B). Where external wind was a pressure (wind acting in combination with axial loads) the internal wind suction coefficient of –0.45 was used. Where external wind was suction (wind acting alone) the internal wind pressure coefficient of 0.3 was used. g. Cgi = 2.0 as per Sentence 4.1.7.1.(6)(c) in the 2006 Building Code. h. The importance factors used to calculate wind loads were 1.0 at the ultimate limit state and 0.75 at the serviceability limit state as per Table 4.1.7.1. in the 2006 Building Code. 4. Ultimate Limit State loads cases were in accordance with Table 4.1.3.2. in the 2006 Building Code. a. 1.4 axial dead load b. 1.25 axial dead load + 1.5 axial snow load c. 1.25 axial dead load + 1.5 axial snow load + 0.4 lateral wind load d. 1.25 axial dead load + 0.5 axial snow load + 1.4 lateral wind load e. 1.4 lateral wind load 5. Serviceability Limits States, based on the Engineering Guide for Wood Frame Construction, were calculated using specified lateral wind loads, and included: a. Deflection limit of stud length/180 for walls with siding, and b. Deflection limit of stud length/360 for walls with brick cladding. 6. Stud resistance was calculated as per CSA O86 and adopted for the Engineering Guide for Wood Frame Construction a. The system factors used were Case 2 load-sharing for bending moment resistance and Case 1 for compression resistance parallel to grain. b. A load duration factor of 1.25 was used where lateral wind acted alone or in combination with axial loads. 7. Fastening requirements are based on the short-term nail resistance values given in CSA O86-01.

Traditionally, diagonal bracing has been provided at the corners of wood framed walls to provide resistance against wind racking forces. Laboratory tests have indicated, however, that the bracing that had been traditionally used contributed relatively little to the overall strength of the wall. Most of the racking resistance was in effect provided by the interior finish. Because of this, the requirements for bracing were deleted in the late 1950’s. (See “Shear Resistance of Wood Frame Walls”, by A.T. Hansen, Building Practice Note 61, Institute for Research in Construction, National Research Council, Ottawa.) Page 236 Appendix A • Volume 2 Where the interior is not finished, however, bracing is necessary if the siding itself or the sheathing does not provide the required racking strength. If panel type siding is used, or if the sheathing consists of plywood, OSB, waferboard, gypsum board, diagonal lumber, or fibreboard sheathing, additional bracing is not considered necessary because of the wind bracing provided by these materials. Where bracing is provided, it must be installed at roughly a 45° angle on each wall and in each storey, extending the full height of the storey. This type of bracing provides considerably greater resistance to wind forces than the traditional bracing, which was found to be relatively ineffective. The permission to omit bracing assumes typical house designs. Some buildings may have reduced resistance to racking forces as a result of their configuration. These include tall narrow buildings in exposed locations with large door or window openings located in the short sides. In such cases, racking resistance can be improved by ensuring that paneled sections are placed adjacent to the openings. The Code does not address the issue of bracing of the structure during construction. It is often necessary to provide temporary bracing until the interior finish or sheathing is installed; however, this is not a Code requirement.

The NLGA “Standard Grading Rules for Canadian Lumber”, referenced in Article 9.3.2.1. refers to two special product standards, SPS-1,"Fingerjoined Structural Lumber,” and SPS-3, “Fingerjoined Stud Lumber - Vertical Use Only”, produced by NLGA. Material identified as conforming to these standards is considered to meet the requirements in this Sentence for joining with a structural adhesive. Lumber fingerjoined in accordance with SPS-3 should be used as a vertical end-loaded member in compression only, where sustained bending or tension-loading conditions are not present, and where the moisture content of the wood will not exceed 19%. Fingerjoined lumber may not be visually regraded or remanufactured into a higher stress grade even if the quality of the lumber containing fingerjoints would otherwise warrant such regrading.

Figure A-9.23.10.6.(3)-A Single Studs on Sides of Openings in Non-Loadbearing Interior Walls not Required to have a Fire-Resistance Rating Appendix A • Volume 2 Page 237 Figure A-9.23.10.6.(3)-B Single Studs at Openings in All Other Walls

Design Assumptions: 1. Roof Load = 0.62 kPa (Asphalt shingle roof) 2. Design Standards: CSA 086-01, “Engineering Design in Wood” 3. Design Assumptions: • The studs are braced from buckling about their weak axis by the attachment of the wall sheathing. • The post is designed for axial loading applied at the centre of the stud cross-section (concentric loading). • Stud grade material has been assumed. • The stud resistance is based on the compressive resistance parallel to grain (P r) and the bearing resistance of the wall plate (Qr). • In the calculation of Pr, a system factor (KH) of 1.0 was used. • In the calculation of Qr, a size factor (Kzcp) of 1.15 was used since the wall plate width is greater than two times the thickness. A length of bearing factor (KB) of 1.0 was used since the stud post can occur at a splice in the wall plate. • The post size has been limited to 5 plies. • The post size is maintained through all storeys directly below the girder truss or beam until the load is transferred to the foundation wall.

Subsection 9.23.13. along with Articles 9.23.3.4., 9.23.3.5., 9.23.6.1., 9.23.9.8., 9.23.15.5., 9.29.5.8., 9.29.5.9., 9.29.6.3. and 9.29.9.3. provide explicit requirements to address resistance to wind and earthquake loads in higher wind and earthquake regions of Canada. Page 238 Appendix A • Volume 2 Table A-9.23.13. Application of Lateral Load Requirements Wind (HWP) Earthquake Sa(0.2) Low to Low to High Extreme High Extreme High Extreme Applicable Moderate Moderate Requirements HWP < 0.80 ≤ HWP HWP ≥ 0.70 < 0.70 < Sa(0.2) ≤ 0.70 0.80 kPa < 1.20 kPa 1.20 kPa Sa(0.2) ≤ 1.8 Sa(0.2) > 1.8 Sa(0.2) ≤ 1.8 Sa(0.2) > 1.8 All All Construction Heavy Construction(1) Light Construction Construction Design requirements in 9.23.16.2., 9.27., X(2) N/A N/A X N/A N/A N/A N/A 9.29. Bracing requirements in X X N/A X X(3)(4) N/A X(4)(5) N/A 9.23.13. Part 4 or X X X X X X X X CWC Guide X = requirements are applicable Notes to Table A-9.23.13.: (1) See Note A-9.23.13.2.(1)(a)(i). (2) Requirements apply to exterior walls only. (3) Requirements apply where lowest exterior frame walls support not more than one floor. (4) All constructions may include the support of a roof in addition to the stated number of floors. (5) Requirements apply where lowest exterior frame walls support not more than two floors.

All 231 locations in Ontario that are identified in Supplementary Standard SB-1, “Climatic and Seismic Data” are locations where the seismic spectral acceleration, Sa(0.2), is less than or equal to 0.70 and the 1-in-50 hourly wind pressure is less than 0.80 kPa. For buildings in these locations, Sentence 9.23.13.1.(2) requires only that exterior walls be braced using the acceptable materials and fastening specified. There are no spacing or dimension requirements for braced wall panels in these buildings. Structural Design for Lateral Wind and Earthquake Loads In cases where lateral load design is required, CWC 2014, “Engineering Guide for Wood Frame Construction,” provides acceptable engineering solutions as an alternative to Part 4. The CWC Guide also contains alternative solutions and provides information on the applicability of the Part 9 prescriptive structural requirements to further assist designers and building officials to identify the appropriate design approach. Appendix A • Volume 2 Page 239

“Heavy construction” refers to buildings with tile roofs, stucco walls or floors with concrete topping, or that are clad with directly-applied heavyweight materials. Heavyweight construction assemblies increase the lateral load on the structure during an earthquake. Assemblies should be considered as heavyweight where their average dead weight is as follows (an additional partition weight of 0.5 kPa per floor is assumed): • floor: 0.5 to 1.5 kPa • roof: 0.5 to 1.0 kPa • wall (vertical area): 0.32 to 1.2 kPa

Article 9.23.13.4. specifies the required characteristics of braced wall bands and their position in the building. Figures A- 9.23.13.4.-A, A-9.23.13.4.-B and A-9.23.13.4.-C illustrate these requirements. Figure A-9.23.13.4.-A Braced Wall Bands in an Example Building Section [Clauses 9.23.13.4.(1)(a), (b) and (d)] Page 240 Appendix A • Volume 2 Figure A-9.23.13.4.-B Lapping Bands and Building Perimeter Within Braced Wall Bands [Clause 9.23.13.4.(1)(c) and Sentence 9.23.13.4.(2)] Figure A-9.23.13.4.-C Braced Wall Bands at Changes in Floor Level in Split-Level Buildings [Sentence 9.23.13.4.(3)] Appendix A • Volume 2 Page 241 A-Table 9.23.13.5. Spacing of Braced Wall Bands and Braced Wall Panels. Identifying adjacent braced wall bands and determining the spacing of braced wall panels and braced wall bands is not complicated where the building plan is orthogonal or there are parallel braced wall bands: the adjacent braced wall band is the nearest parallel band. Figure Table A-9.23.13.5.-A illustrates spacing. Figure Table A-9.23.13.5.-A Spacing of Parallel Braced Wall Bands and Spacing of Braced Wall Panels Identifying and Spacing Adjacent Non-Parallel Braced Wall Bands Identifying the adjacent braced wall band and the spacing between braced wall bands is more complicated where the building plan is not orthogonal. Where the plan is triangular, all braced wall bands intersect with the subject braced wall band. The prescriptive requirements in Part 9 do not apply to these cases and the building must be designed according to Part 4 with respect to lateral load resistance. Where the braced wall bands are not parallel, the adjacent band is identified as follows using Figure Table A-9.23.13.5.-B as an example: 1. Determine the mid-point of the centre line of the subject braced wall band (A); 2. Project a perpendicular line from this mid-point (B); 3. The first braced wall band encountered is the adjacent braced wall band (C); 4. Where the projected line encounters an intersection point between two braced wall bands, either wall band may be identified as the adjacent braced wall band (complex cases). Page 242 Appendix A • Volume 2 The spacing of non-parallel braced wall bands is measured as the greatest distance between the centre lines of the bands. Figure Table A-9.23.13.5.-B Identification and Spacing of Adjacent Non-Parallel Braced Wall Bands Appendix A • Volume 2 Page 243

Where the perimeter foundation walls in basements and crawl spaces extend from the footings to the underside of the supported floor, these walls perform the same function as braced wall bands with braced wall panels. All other braced wall bands in the basement or crawl space that align with bands with a wood-based bracing material on the upper floors need to be constructed with braced wall panels,which must be made of a wood-based bracing material, masonry or concrete. See Figure

Braced Wall Bands in Basements or Crawl Spaces with Optional and Required Braced Wall Panels Page 244 Appendix A • Volume 2

Figure A-9.23.13.5.(3)-A Porch Roof Framing Perpendicular to Wall Framing Between Floors Figure A-9.23.13.5.(3)-B Porch Roof Framing Parallel to Wall Framing Between Floors Appendix A • Volume 2 Page 245

Bracing. Braced wall panels constructed with gypsum board provide less resistance to lateral loads than panels constructed with OSB, waferboard, plywood or diagonal lumber; Sentence (5) therefore limits the use of gypsum board to interior walls. Sentence (6) further limits its use to provide the required lateral resistance by requiring that walls not more than 15 m apart be constructed with panels made of wood or wood-based sheathing. See Figure A-9.23.13.6.(5) and (6). Figure A-9.23.13.6.(5) and (6) Braced Wall Panels Constructed of Wood-Based Material

Sentence 9.23.13.11.(2) requires that the connections used in wood roof trusses be designed in conformance with Subsection 4.3.1. The designer of wood trusses should be skilled in the work concerned, since wood roof trusses are complex structures which depend on a number of components (chord members, web members, cross-bracing, connectors) working together to function safely. This complexity precludes the standardization of truss design into tables comprehensive enough to satisfy the variety of roof designs required by the housing industry.

A method for determining water absorption is described in ASTM D1037, “Standard Test Methods for Evaluating the Properties of Wood-Base Fiber and Particle Panel Materials”. The treatment to reduce water absorption may be considered to be acceptable if a 300 mm x 300 mm sample when treated on all sides and edges does not increase in weight by more than 6% when tested in the horizontal position.

CSA 0437.0, “OSB and Waferboard”, requires that Type O (aligned or oriented) panels be marked to show the grade and the direction of face alignment. Page 246 Appendix A • Volume 2

Figure A-9.24.3.2.(3) Steel Stud Header Detail

It is important to understand the difference between the functions of a vapour barrier and an air barrier. Some materials perform both functions, while others are only intended to perform one of the two. Vapour barrier materials are intended to restrict the movement of water vapour due to vapour pressure differentials, which are created by differences in temperature and moisture content, while air barrier materials are intended to restrict the movement of air due to air pressure differentials. A vapour barrier does not have to be continuous or sealed to perform its function of reducing the amount of water vapour that moves across an assembly, but an air barrier must be continuous and fully sealed to prevent the movement of air across the assembly. Further information can be found in “The difference between a vapour barrier and an air barrier,” by Quirouette, R. L., Building Performance Section, Division of Building Research, National Research Council Canada, BPN 54, July 1985.

Part 9 has no requirements for flame-spread ratings of insulation materials since these are seldom exposed in parts of buildings where fires are likely to start. Certain of the insulating material standards referenced in Sentence 9.25.2.2.(1) do include flame-spread rating criteria. These are included either because the industry producing the product wishes to demonstrate that their product does not constitute a fire hazard or because the product is regulated by authorities other than building authorities (e.g., Hazardous Products Act). However, the Code cannot apply such requirements to some materials and not to others. Hence, these flame-spread rating requirements are excepted in referencing these standards.

For thermal insulation to be effective, it must not be short-circuited by convective air flow through or around the material. If low density fibrous insulation is installed with an air space on both sides of the insulation, the temperature differential between the warm and cold sides will drive convective air flow around the insulation. If foam plastic insulation is spot adhered to a back-up wall or adhered in a grid pattern to an air permeable substrate, and is not sealed at the joints and around the perimeter, air spaces between the insulation and the substrate will interconnect with spaces behind the cladding. Any temperature or air pressure differential across the insulation will again lead to short circuiting of the insulation by air flow. Thermal insulation must therefore be installed in full and continuous contact with the air barrier or another continuous component with low air permeance. (See Appendix note A-9.25.5.1.(1) for examples of low-air-permeance materials.) Appendix A • Volume 2 Page 247

The addition of insulation into exterior walls of existing wood-frame buildings increases the likelihood of damage to framing and cladding components as a result of moisture accumulation. Many older homes were constructed with little or no regard for protection from vapour transmission or air leakage from the interior. Adding thermal insulation will substantially reduce the temperature of the siding or sheathing in winter months, possibly leading to condensation of moisture at this location. Defects in exterior cladding, flashing and caulking could result in rain entering the wall cavity. This moisture, if retained by the added insulation, could initiate the process of decay. Steps should be taken therefore, to minimize these effects prior to the retrofit of any insulation. Any openings in walls that could permit leakage of interior heated air into the wall cavity should be sealed. The inside surface should be coated with a low-permeability paint to reduce moisture transfer by diffusion. Finally, the exterior siding, flashing and caulking should be checked and repaired if necessary to prevent rain penetration.

Typical masonry cavity wall construction techniques do not lend themselves to the prevention of entry of rainwater into the wall space. For this reason, loose-fill insulation used in such space must be of the water repellent type. A test for water- repellency of loose-fill insulation suitable for installation in masonry cavity walls can be found in ASTM C516, “Standard Specification for Vermiculite Loose Fill Insulation”.

The majority of moisture problems resulting from condensation of water vapour in walls and ceiling/attic spaces are caused by the leakage of moist interior heated air into these spaces rather than by the diffusion of water vapour through the building envelope. Protection against such air leakage must be provided by a system of air-impermeable materials joined with leak-free joints. Generally, air leakage protection can be provided by the use of air-impermeable sheet materials, such as gypsum board or polyethylene of sufficient thickness, when installed with appropriate structural support. However, the integrity of the airtight elements in the air barrier system can be compromised at the joints and here special care must be taken in design and construction to achieve an effective air barrier system. Although Section 9.25. refers separately to vapour barriers and airtight elements in the air barrier system, these functions in a wall or ceiling assembly of conventional wood frame construction are often combined as a single membrane which acts as a barrier against moisture diffusion and the movement of interior air into insulated wall or roof cavities. Openings cut through this membrane, such as for electrical boxes, provide opportunities for air leakage into concealed spaces, and special measures must be taken to make such openings as airtight as possible. Attention must also be paid to less obvious leakage paths, such as holes for electric wiring, plumbing installations, wall-ceiling and wall-floor intersections, and gaps created by shrinkage of framing members. In any case, air leakage must be controlled to a level where the occurrence of condensation will be sufficiently rare, or the quantities accumulated sufficiently small, and drying sufficiently rapid, to avoid material deterioration and the growth of mould and fungi. Generally, the location in a building assembly of the airtight element of the air barrier system is not critical; it can restrict air leakage whether it is located near the outer surface of the assembly, near the inner surface or at some intermediate location. However, if a material chosen to act as an airtight element in the air barrier system also has the characteristics of a vapour barrier (i.e., low permeability to water vapour), its location must be chosen more carefully in order to avoid moisture problems. (See Appendix Notes A-9.25.4.3.(2) and A-9.25.5.1.(1)). Page 248 Appendix A • Volume 2 In some assemblies, an airtight element in the air barrier system is the interior finish, such as gypsum board, which is sealed to framing members and adjacent components by gaskets, caulking, tape or other methods to complete the air barrier system. In such cases, special care in sealing joints in a separate vapour barrier is not critical. This approach often uses no separate vapour barrier but relies on appropriate paint coatings to give the interior finish sufficient resistance to water vapour diffusion that it can provide the required vapour diffusion protection. Section 9.25. allows for such innovative techniques, as well as the more traditional approach of using a continuous sheet, such as polyethylene, to act as an “air/vapour barrier”. Further information is available in “Moisture Problems in Houses”, by A.T. Hansen, Canadian Building Digest 231, available from the Institute for Research in Construction, National Research Council of Canada, Ottawa K1A 0R6. a1 9.25.3.3.(9) Reserved. A-9.25.4.2.(2) Vapour Barrier Materials in Foundation Wall Assemblies Enclosing Basements or Heated Crawl Spaces. In the summer, solar heating can cause condensation to form on the wall-facing side of polyethylene membranes that are installed on the warm side of foundation wall assemblies enclosing a basement or heated crawl space. Moisture in the foundation wall due to wind-driven rain is driven to the interior when the above-ground portion of the wall is exposed to solar heating. Variable-permeance vapour barrier materials allow moisture to dissipate into the basement or heated crawl space during the summer and have thus been shown to minimize the formation of condensation in foundation wall assemblies. These materials have proven effective whether installed continuously over the full area of the foundation wall or continuously over not less than the top half of the full height of the wall area, starting from the above-ground portion, with a polyethylene membrane installed over the remaining bottom portion. Sentence 9.25.4.2.(2) is not intended to preclude the use of variable-permeance vapour barriers in above-grade wall assemblies. However, when contemplating their use in such an application, consideration should be given to the climatic conditions at the building's location. A-9.25.4.2.(3) Normal Conditions. The requirement for a 60 ng/(Pa·s·m2) vapour barrier stated in Sentence 9.25.4.2.(1) is based on the assumption that the building assembly is subjected to conditions that are considered normal for typical residential occupancies, and business and personal services occupancies. However, where the intended use of an occupancy includes facilities or activities that will generate a substantial amount of moisture indoors during the heating season, such as swimming pools, greenhouses, laundromats, and any continuous operation of hot tubs and saunas, the building envelope assemblies would have to demonstrate acceptable performance levels in accordance with the requirements in Part 5. Appendix A • Volume 2 Page 249

The requirements of CAN/CGSB-51.33-M, “Vapour Barrier Sheet, Excluding Polyethylene, for Use in Building Construction,” were developed for paper-based vapour barriers, which are not susceptible to deterioration under prolonged exposure to direct ultraviolet (UV) radiation. Since the publication of the last edition of this standard in 1989, non- polyethylene vapour barriers have become available that are susceptible to UV-induced deterioration. These vapour barriers must be protected by a covering or installed in locations where they will not be exposed to direct UV radiation after the completion of construction. In addition, the vapour barrier manufacturer's guidance regarding the maximum allowable time of exposure to direct UV radiation should be followed where provided. Exposure to direct UV radiation most commonly occurs around window openings.

Assemblies in which the vapour barrier is located partway through the insulation meet the intent of this Article provided it can be shown that the temperature of the vapour barrier will not fall below the dew point of the heated interior air.

Low Air- and Vapour-Permeance Materials and Implications for Moisture Accumulation The location in a building assembly of a material with low air permeance is not critical; the material can restrict outward movement of indoor air whether it is located near the outer surface of the assembly, near the inner surface, or at some intermediate location, and such restriction of air movement is generally beneficial, whether or not the particular material is designated as part of the air barrier system. However, if such a material also has the characteristics of a vapour barrier (i.e., low permeability to water vapour) and low thermal resistance, its location must be chosen more carefully in order to avoid moisture accumulation. Any moisture from the indoor air which diffuses through the inner layers of the assembly or is carried by air leakage through those layers may be prevented from diffusing or being transferred through the assembly by a low air- and vapour- permeance material. This moisture transfer will usually not cause a problem if the material is located where the temperature is above the dew point of the indoor air; the water vapour will remain as vapour, the humidity level in the assembly will come to equilibrium with that of the indoor air, further accumulation of moisture will cease or stabilize at a low rate, and no harm will be done. But if the low air- and vapour-permeance material is located where the temperature is below the dew point of the air at that location, water vapour will condense and accumulate as water or ice, which will reduce the humidity level and encourage the movement of more water vapour into the assembly. If this temperature remains below the dew point for any length of time, significant moisture could accumulate. When warmer weather returns, the presence of a material with low water vapour permeance can retard drying of the accumulated moisture. Moisture which remains into warmer weather can support the growth of decay organisms. Due consideration should be given to the properties and location of any material in the building envelope, including paints, liquid-applied or sprayed-on and trowelled-on materials. It is recognized that assemblies that include low air- and vapour- permeance materials are acceptable, but only where these materials are not susceptible to damage from moisture or where they can accommodate moisture (for example insulated concrete walls). Further information on the construction of basement walls may be found in • Performance Guidelines for Basement Envelope Systems and Materials,” published by NRC-IRC. • Best Practice Guide Full-Height Basement Insulation Guide, 2008 published by MMAH Cladding Different cladding materials have different vapour permeances and different degrees of susceptibility to moisture deterioration. They are each installed in different ways that are more or less conducive to the release of moisture that may accumulate on the inner surface. Sheet or panel-type cladding materials, such as metal sheet, have a vapour permeance less than 60 ng/(Pa·s·m2). Sheet metal cladding that has lock seams also has a low air leakage characteristic and so must be installed outboard of a drained and vented air space. Assemblies clad with standard residential vinyl or metal strip siding do not require additional protection as the joints are not so tight as to prevent the dissipation of moisture. Page 250 Appendix A • Volume 2 Sheathing Like cladding, sheathing materials have different vapour permeances and different degrees of susceptibility to moisture deterioration. Low-permeance sheathing may serve as the vapour barrier if it can be shown that the temperature of the interior surface of the sheathing will not fall below that at which saturation will occur. This may be the case where insulating sheathing is used. Thermal Insulation Where low-permeance foamed plastic is the sole thermal insulation in a building assembly, the temperature of the inner surface of this element will be close to the interior temperature. If the foamed plastic insulation has a permeance below 60 ng/(Pa·s·m2), it can fulfill the function of a vapour barrier to control condensation within the assembly due to vapour diffusion. However, where low-permeance thermal insulation is installed on the outside of an insulated frame wall, the temperature of the inner surface of the insulation may fall below the dew point. In this case, the function of vapour barrier has to be provided by a separate building element installed on the warm side of the assembly. Normal Conditions The required minimum ratios given in Table 9.25.5.2. are based on the assumption that the building assembly is subjected to conditions that are considered normal for typical residential occupancies, and business and personal services occupancies. However, where the intended use of an occupancy includes facilities or activities that will generate a substantial amount of moisture indoors during the heating season, such as swimming pools, greenhouses, the operation of a laundromat or any continuous operation of hot tubs and saunas, the building envelope assemblies would have to demonstrate acceptable performance levels in accordance with the requirements in Part 5.

The air leakage characteristics and water vapour permeance values for a number of colnmon materials are given in Table A-9.25.5.1.(1). These values are provided on a generic basis; proprietary products may have values differing somewhat from those in the Table (consult the manufacturer’s current data sheets for their products' values). The values quoted are for the material thickness listed. Water vapour permeance is inversely proportional to thickness: therefore, greater thicknesses will have lower water vapour permeance values. Appendix A • Volume 2 Page 251 Table A-9.25.5.1.(1) Air and Vapour Permeance Values(1) Air Leakage Characteristic, Water Vapour Permeance, Material L/(s•m2) at 75 Pa (Dry CuP) (Air Permeance) 60 ng/(Pa•s•m2) Sheet and panel-type materials 12.7 mm gypsum board 0.02 2600 • painted (1 coat primer) negligible 1300 • painted (1 coat primer + 2 coats latex paint) negligible 180 12.7 mm foil-backed gypsum board negligible negligible 12.7 mm gypsum board sheathing 0.0091 1373 6.4 mm plywood 0.0084 23 -74 11 mm oriented strandboard 0.0108 44 (range) 12.5 mm cement board 0.147 590 plywood (from 9.5 mm to 18 mm) negligible - 0.01 40 - 57 fibreboard sheathing 0.012 - 1.91 100 - 2900 17 mm wood sheathing high - depends on no. of joints 982 Insulation 27 mm foil-faced polyisocyanurate negligible 4.3 27 mm paper-faced polyisocyanurate negligible 61.1 25 mm extruded polystyrene negligible 23 - 92 25 mm expanded polystyrene (Type 2) 0.0214 86 - 160 fibrous insulations very high very high 25 mm polyurethane spray foam - low density 0.011 894 - 3791 25 mm polyurethane spray foam - medium density negligible 96(2) Membrane-type materials asphalt-impregnated paper (10 min paper) 0.0673 370 asphalt-impregnated paper (30 min paper) 0.40 650 asphalt-impregnated paper (60 min paper) 0.44 1800 water-resistive barriers (9 materials) negligible - 4.3 30 - 1200 0.15 mm polyethylene negligible 1.6 - 5.8 asphalt-saturated felt (#15) 0.153 290 building paper 0.2706 170 - 1400 spun-bonded polyolefin film (expanded) 0.9593 3646 Other materials brick (6 materials) negligible 102 - 602 metal negligible negligible mortar mixes (4 materials) negligible 13 - 690 stucco negligible 75 - 240 50 mm reinforced concrete (density: 2 330 kg/m3) negligible 23 Page 252 Appendix A • Volume 2 Notes to Table A-9.25.5.1.(1) (1) Air leakage and vapour permeance values derived from: • Bombaru, D., Jutras, R. and Patenaude, A. Air Permeance of Building Materials. Summary Report prepared by AIR-INS Inc. for Canada Mortgage and Housing Corporation, Ottawa, 1988. Values indicate properties of tested materials only; values for specific products may vary significantly. • Details of Air Barrier Systems for Houses. Tarion Warranty Corporation (formerly Ontario New Home Warranty Program), Toronto, 1993. • Kumaran, M.K., el al., ASHRAE Research Report 1018 RP, A Thermal and Moisture Transport Property Database for Common Building and Insulating Materials. • Kumaran, M.K., Lackey, J., Normandin, N., van Reenen, D., Tariku, F., Summary Report from Task 3 of MEWS Project at the Institute for Research in Construction-Hygrothermal Properties of Several Building Materials, IRC- RR-110, March 2002. • Mukhopadhyaya, P., Kumarai M.K., et al., Hygrothermal Properties of Exterior Claddings, Sheathing Boards, Membranes and lnsulation Materials for Building Envelope Design, Proceedings of Thermal Performance of the Exterior Envelopes of Whole Building X, Clearwater, Florida, December 2-7, 2007, pp. 1-16 (NRCC-50287). (2) This water vapour permeance value is for a 25 mm thick core layer of medium density polyurethane spray foam. When installed in the field, a low permeance resin layer forms where the foam is in contact with the substrate. The water vapour permeance of the installed foam, were it measured including the resin layer, would therefore likely be lower than the value listed in the Table.

The requirements in Article 9.25.5.2. aim to reduce the risk of condensation being introduced into wall assemblies due to the water vapour permeance of the outboard materials. Research has confirmed that the reduced condensation potential of exterior continuous insulation with a thermal resistance of at least 0.7 (m 2·K)/W and a water vapour permeance between 30 and 1 800 ng/(Pa·s·m2) compares to reference assemblies without exterior insulation in a given geographic location and climatic exposure.

Wood-based sheathing materials, such as plywood and OSB, that are not more than 12.5 mm thick are exempt from complying with Sentence 9.25.5.1.(1) because wood has an adaptive vapour permeance based on relative humidity: it has a low vapour permeance in an environment with low relative humidity and a higher vapour permeance in an environment with high relative humidity. (See Figure A-9.25.5.1.(3)) This adaptive vapour permeance means that wood-based materials located on the outboard side of an assembly in winter, where the RH is typically 75% or higher, are relatively vapour-open, thus allowing greater vapour movement. The same wood-based material located on the inboard side of an assembly, where the RH is typically much lower in winter, has a low vapour permeance, thus mitigating the movement of vapour. Appendix A • Volume 2 Page 253 Figure A-9.25.5.1.(3) Adaptive Water Vapour Permeance of Wood-Based Sheathing Materials Page 254 Appendix A • Volume 2

Article 9.25.5.2. specifies that a low air- and vapour-permeance material must be located on the warm face of the assembly, outboard of a vented air space, or within the assembly at a position where its inner surface is likely to be warm enough for most of the heating season such that no significant accumulation of moisture will occur. This last position is defined by the ratio of the thermal resistance values outboard and inboard of the innermost impermeable surface of the material in question. The design values given in Table 9.25.5.2. are based on the assumption that the building includes a mechanical ventilation system (between 0.3 and 0.5 air changes per hour), a 60 ng/(Pa·s·m2) vapour barrier, and an air barrier (values between 0.024 and 0.1 L/(s·m2) through the assembly were used). The moisture generated by occupants and their use of bathrooms, cleaning, laundry and kitchen appliances was assumed to fall between 7.5 and 11.5 L per day. It has been demonstrated through modelling under these conditions that assemblies constructed according to the requirements in Table 9.25.5.2. do not lead to moisture accumulation levels that may lead to deterioration as long as the average monthly vapour pressure difference between the exterior and interior sides over the heating season does not increase above 750 Pa, which would translate into an interior relative humidity (RH) of 35% in colder climates and 60% in mild climates. Health Canada recommends indoor relative humidities between 35% and 50% for healthy conditions. ASHRAE accepts a 30% to 60% range. Environments that are much drier tend to exacerbate respiratory problems and allergies; more humid environments tend to support the spread of microbes, moulds and dust mites, which can adversely affect health. In most of Canada in the winter, indoor RH is limited by the exterior temperature and the corresponding temperature on the inside of windows. During colder periods, indoor RH higher than 35% will cause significant condensation on windows. When this occurs, occupants are likely to increase the ventilation to remove excess moisture. Although indoor RH may exceed 35% for short periods when the outside temperature is warmer, the criteria provided in Table 9.25.5.2. will still apply. Where higher relative humidities are maintained for extended periods in these colder climates, the ratios listed in the Table may not provide adequate protection. Table 9.25.5.2. cannot be used for occupancies that require that RH be maintained above 35% throughout the year and for those interior spaces that support activities, such as swimming, that create high relative humidities. In these cases the position of the materials must be determined according to Part 5. lt should be noted that Part 9 building envelopes in regions with colder winters have historically performed acceptably when the indoor RH does not exceed 35% over most of the heating season. With tighter building envelopes, it is possible to raise indoor RH levels above 35%. There is no information, however, on how Part 9 building envelopes will perform when exposed to these higher indoor RH levels for extended periods during the heating season over many years. Operation of the ventilation system, as intended to remove indoor pollutants, will maintain the lower RH levels as necessary. The method of calculating the inboard to outboard thermal resistance ratio is illustrated in Figure A-9.25.5.2. The example wall section shows three planes where low air- and vapour-permeance materials have been installed. A vapour barrier, installed to meet the requirements of Subsection 9.25.4., is on the warm side of the insulation consistent with Clause 9.25.1.2.(1)(a) and Sentences 9.25.4.1.(1) and 9.25.4.3.(2). The vinyl siding has an integral drained and vented air space consistent with Clause 9.25.1.2.(1)(c). The position of the interior face of the low-permeance insulating sheathing, however, must be reviewed in terms of its thermal resistance relative to the overall thermal resistance of the wall, and the climate where the building is located. Comparing the RS1 ratio from the example wall section with those in Table 9.25.5.2. indicates that this wall would be acceptable in areas with Celsius degree-day values up to 7999, which includes, for example, Geraldton. (Degree-day values for various locations in Ontario are provided in MMAH Supplementary Standard SB-1. A similar calculation would indicate that, for a similar assembly but with a 140 mm stud cavity filled with an RSI 3.52 batt, the ratio would be 0.28. Thus such a wall could be used in areas with Celsius degree-day values up to 4999, which includes, for example, Ottawa. Similarly, if half the thickness of the same low permeance sheathing were used, the ratio with an 89 mm cavity would be 0.25, permitting its use in areas with Celsius degree-day values up to 4999. The ratio with a 140 mm cavity would be 0.16; thus this assembly could not be used anywhere, since this ratio is below the minimum permitted in Table A-9.25.5.2. Appendix A • Volume 2 Page 255 Div. B • A-9.25.5.2. 2012 Building Code Compendium Table A-9.25.5.2. shows the minimum thicknesses of low permeance insulating sheathing necessary to satisfy Article 9.25.5.2. in various degree-day zones for a range of resistivity values of insulating sheathing. These thicknesses are based on the detail shown in Figure A-9.25.5.2. but could also be used with cladding details, such as brick veneer or wood siding, which provide equal or greater outboard thermal resistance. Figure A-9.25.5.2. Example of a Wall Section Showing Thermal Resistance Inboard and Outboard of a Plane of Low Air and Vapour Permeance Table A-9.25.5.2. Minimum Thicknesses of Low Permeance Insulating Sheathing 38 x 89 mm Framing 38 x 140 mm Framing Min. Min. Sheathing Thickness, mm Min. Sheathing Thickness, mm Celsius Heating Min. Outboard Min. Outboard RSI Sheathing Thermal Resistance, Sheathing Thermal Resistance, Degree-days Thermal Thermal Ratio RSI/mm RSI/mm Resistance, RSI Resistance, RSI 0.0300 0.0325 0.0350 0.0400 0.0300 0.0325 0.0350 0.0400 ≤ 4999 0.20 0.46 10 10 9 8 0.72 19 17 16 14 5000 to 5999 0.30 0.69 18 17 16 14 1.07 31 28 26 23 6000 to 6999 0.35 0.81 22 20 19 16 1.25 37 34 32 28 7000 to 7999 0.40 0.92 26 24 22 19 1.43 43 39 37 32 8000 to 8999 0.50 1.16 34 31 29 25 1.79 55 50 47 41 9000 to 9999 0.55 1.27 37 34 32 28 1.97 61 56 52 45 10000 to 10999 0.60 1.39 41 38 35 31 2.15 67 61 57 50 11000 to 11999 0.65 1.50 45 42 39 34 2.33 73 67 62 54 ≥ 12000 0.75 1.73 53 49 45 40 2.69 85 78 72 63 Column 1 2 3 4 5 6 7 8 9 10 11 12 References (1) Exposure Guidelines for Residential Indoor Air Quality, Environmental Health Directorate, Health Protection Branch, Health Canada, Ottawa, April 1987 (Revised July 1989). (2) ANSI/ASHRAE 62, “Ventilation for Acceptable Indoor Air Quality." Page 256 Appendix A • Volume 2

Decks, balconies, exterior walkways and similar exterior surfaces effectively serve as roofs where these platforms do not permit the free drainage of water through the deck. When water is driven by wind across the deck (roof) surface, it can be driven upward when it encounters an interruption.

Where shingles or shakes have been chemically treated with a preservative or a fire retardant, the fastener should be of a material known to be compatible with the chemicals used in the treatment.

Drainage of water from decks and other platforms that effectively serve as roofs will be blocked by walls, and blocked or restricted by guards where significant lengths and heights of material are connected to the deck. Without proper flashing at such roof-wall junctions or roof-guard junctions, water will generally leak into the adjoining elements and can penetrate into supporting assemblies below. Exceptions include platforms where waterproof curbs of sufficient height are cast-in or where the deck and wall or guard are unit-formed. In these cases, the monolithic deck-wall or deck-guard junctions will minimize the likelihood of water ingress. (See also Appendix Note A-9.26.1.1.(1).)

While underlayment has not traditionally been required by the Code, some shingle manufacturers require its use beneath their products.

Where concrete roof tiles are to be installed, the dead load imposed by this material should be considered in determining the minimum sizes and maximum spans of the supporting roof members.

While Part 9 permits the installation of exterior insulation finish systems on walls with cold-formed steel stud framing, the design of loadbearing steel walls is outside the scope of Part 9 and is addressed in Part 4 (see Sentence 9.24.1.1.(2)).

Part 5 and Part 9 of the Building Code recognize that mass walls and face-sealed, concealed barrier and rainscreen assemblies have their place in the Canadian context. Mass walls are generally constructed of cast-in-place concrete or masonry. Without cladding or surface finish, they can be exposed to precipitation for a significant period before moisture will penetrate from the exterior to the interior. The critical characteristics of these walls are related to thickness, mass, and moisture transfer properties, such as shedding, absorption and moisture diffusion. Face-sealed assemblies have only a single plane of protection. Sealant installed between cladding elements and other envelope components is part of the air barrier system and is exposed to the weather. Face-sealed assemblies are appropriate where it can be demonstrated that they will provide acceptable performance with respect to the health and safety of the occupants, the operation of building services and the provision of conditions suitable for the intended occupancy. These assemblies, however, require more intensive, regular and on-going maintenance, and should only be selected on the basis of life-cycle costing considering the risk of failure and all implications should failure occur. Climate loads such as wind-driven rain, for example, should be considered. Face-sealed assemblies are not recommended where the building owner may not be aware of the maintenance issue or where regular maintenance may be problematic. Concealed barrier assemblies include both a first and second plane of protection. The first plane comprises the cladding, which is intended to handle the majority of the precipitation load. The second plane of protection is intended to handle any water that penetrates the cladding plane. It allows for the dissipation of this water, primarily by gravity drainage, and provides a barrier to further ingress. Appendix A • Volume 2 Page 257 Like concealed barrier assemblies, rainscreen assemblies include both a first and second plane of protection. The first plane comprises the cladding, which is designed and constructed to handle virtually all of the precipitation load. The second plane of protection is designed and constructed to handle only very small quantities of incidental water; composition of the second plane is described in Appendix Note A-9.27.3.1. In these assemblies, the air barrier system, which plays a role in controlling precipitation ingress due to air pressure difference, is protected from the elements. (See Figure A-9.27.2.) Figure A-9.27.2. Generic Rainscreen Assemblies

The total prevention of precipitation ingress into wall assemblies is difficult to achieve and, depending on the wall design and construction, may not be absolutely necessary. The amount of moisture that enters a wall, and the frequency with which this occurs, must be limited. The occurrence of ingress must be sufficiently rare, accumulation sufficiently small and drying sufficiently rapid to prevent the deterioration of moisture-susceptible materials and the growth of fungi.

Part 9 provides guidance to assist in determining the minimum levels of protection from precipitation to be provided by cladding assemblies. Article 9.27.2.2. describes the minimum cladding assembly configuration. Designers must still consider local accepted good practice, demonstrated performance and the specific conditions to which a particular wall will be exposed when designing or selecting a cladding assembly. A.9.27.3.1. Second Plane of Protection. As specified in Sentence 9.27.3.1.(1), the second plane of protection consists of a drainage plane with an appropriate material serving as the inner boundary and flashing to dissipate rainwater or meltwater to the exterior. Page 258 Appendix A • Volume 2 Drainage Plane Except for masonry walls, the simplest configuration of a drainage plane is merely a vertical interface between materials that will allow gravity to draw the moisture down to the flashing to allow it to dissipate to the exterior. It does not necessarily need to be constructed as a clear drainage space (air space). For masonry walls, an open rainscreen assembly is required; that is, an assembly with first and second planes of protection where the drainage plane is constructed as a drained and vented air space. Such construction also constitutes best practice for walls other than masonry walls. Section 9.20. requires drainage spaces of 25 mm for masonry veneer walls and 50 mm for cavity walls. In other than masonry walls, the drainage space in an open rainscreen assembly should be at least 10 mm deep. Drainage holes must be designed in conjunction with the flashing. Sheathing Membrane The sheathing membrane described in Article 9.27.3.2. is not a waterproof material. When installed to serve as the inner boundary of the second plane of protection, and when that plane of protection includes a drainage space at least 10 mm deep, the performance of the identified sheathing membrane has been demonstrated to be adequate. This is because the material is expected to have to handle only a very small quantity of water that penetrates the first plane of protection. If the 10 mm drainage space is reduced or interrupted, the drainage capacity and the capillary break provided by the space will be reduced. In these cases, the material selected to serve as the inner boundary may need to be upgraded to provide greater water resistance in order to protect moisture-susceptible materials in the backing wall. Appropriate Level of Protection It is recognized that many cladding assemblies with no space or with discontinuous space behind the cladding, and with the sheathing membrane material identified in Article 9.27.3.2., have provided acceptable performance with a range of precipitation loads imposed on them. Vinyl and metal strip siding, and shake and shingle cladding, for example, are installed with discontinuous drained spaces, and have demonstrated acceptable performance in most conditions. Lapped wood and composite strip sidings, depending on their profiles, may or may not provide discontinuous spaces, and generally provide little drainage. Cladding assemblies with limited drainage capability that use a sheathing membrane meeting the minimum requirements are not recommended where they may be exposed to high precipitation loads or where the level of protection provided by the cladding is unknown or questionable. Local practice with demonstrated performance should be considered. (See also Appendix Note A-9.27.2.2.(4))

The shape of a joint is critical to its ability to shed water. Tongue and groove, and lapped joints can shed water if oriented correctly. Butt joints can drain to either side and so should not be used unless they are sealed. However, detailing of joints requires attention not just to the shape of the joint but also to the materials that form the joint. For example, even if properly shaped, the joints in insulating sheathing with an integral sheathing membrane could not be expected to shed water if the insulating material absorbs water, unless the membrane extends through the joints.

Article 9.23.17.1., Required Sheathing, indicates that sheathing must be installed only where the cladding requires intermediate fastening between supports (studs) or where the cladding requires a solid backing. Cladding such as brick or panels would be exempt from this requirement and in these cases a double layer of sheathing membrane would generally be needed. The exception (Article 9.27.3.6.) applies only to those types of cladding that provide a face seal to the weather. Appendix A • Volume 2 Page 259

The purpose of sheathing membrane on walls is to reduce air infiltration and to control the entry of wind-driven rain. Certain types of cladding consisting of very large sheets or panels with well-sealed joints will perform this function, eliminating the need for sheathing membrane. This is true of the metal cladding with lock-seamed joints sometimes used on mobile homes. However, it does not apply to metal or plastic siding applied in narrow strips which is intended to simulate the appearance of lapped wood siding. Such material does not act as a substitute for sheathing membrane since it incorporates provision for venting the wall cavity and has many loosely-fitted joints which cannot be counted on to prevent the entry of wind and rain. Furthermore, certain types of sheathing systems can perform the function of the sheathing membrane. Where it can be demonstrated that a sheathing material is at least as impervious to air and water penetration as sheathing membrane and that its jointing system results in joints that are at least as impervious to air and water penetration as the material itself, sheathing membrane may be omitted.

Horizontal Offsets Where a horizontal offset in the cladding is provided by a single cladding element, there is no joint between the offset and the cladding above. In this case, and provided the cladding material on the offset provides effective protection for the construction below, flashing is not required. Changes in Substrate In certain situations, flashing should be installed at a change of substrate: for example, where stucco cladding is installed on a wood-frame assembly, extending down over a masonry or cast-in-place concrete foundation and applied directly to it. Such an application does not take into account the potential for shrinkage of the wood frame and cuts off the drainage route for moisture that may accumulate behind the stucco on the frame construction. Figure A-9.27.3.8.(1) Flashing at Change in Substrate A.9.27.3.8.(3) Flashing Over Curved-Head Openings. The requirement for flashing over openings depends on the vertical distance from the top of the trim over the opening to the bottom of the eave compared to the horizontal projection of the eave. In the case of curved-head openings, the vertical distance from the top of the trim increases as one moves away from the centre of the opening. For these openings, the top of the trim must be taken as the lowest height before the trim becomes vertical. (See Figure A-9.27.3.8.(3)) Page 260 Appendix A • Volume 2 Figure A-9.27.3.8.(3) Flashing Over Curved-Head Openings

Flashing Configuration A 6% slope is recognized as the minimum that will provide effective flashing drainage. The 10 mm vertical lap over the building element below and the 5 mm offset are prescribed to reduce transfer by capillarity and surface tension. Figure A-9.27.3.8.(4) illustrates two examples of flashing configurations. Figure A-9.27.3.8.(4) Examples of Flashing Configurations Showing Upstands, Horizontal Offsets and Vertical Laps Maintaining Positive Slope Sentence 9.27.3.8.(4) requires that the minimum 6% flashing slope remain after expected shrinkage of the building frame. Similarly, Sentence 9.26.3.1.(4) requires that a positive slope remain on roofs and similar assemblies after expected shrinkage of the building frame. For Part 9 wood-frame construction, expected wood shrinkage can be determined based on the average equilibrium moisture content (MC) of wood, within the building envelope assembly. According the Canadian Wood Council’s Wood Reference Handbook, the equilibrium moisture content (equilibrium MC) for wood in Ontario is 8%. Appendix A • Volume 2 Page 261 For three-storey construction to which Part 9 applies, the cumulative longitudinal shrinkage is negligible. Shrinkage need only be calculated for horizontal framing members using the following formula (from Introduction to Wood Building Technology, Canadian Wood Council, Ottawa, 1997): Shrinkage = (total horizontal member height) x (initial MC - equilibrium MC) x (0.002)

Many windows are configured in such a way that a line of sealant is the only protection against water ingress at the sill-to- cladding joint & a location that is exposed to all of the water that flows down the window. In the past, many windows were constructed with self-flashing sills & sills that extend beyond the face of the cladding and have a drip on the underside to divert water away from the sill-to-cladding joint. This sill configuration was considered to be accepted good practice and is recognized today as providing a degree of redundancy in precipitation protection. Self-flashing sills are sills that • slope toward the exterior where the sills have an upward facing surface that extends beyond the jambs, • where installed over a masonry sill, extend not less than 25 mm beyond the inner face of that sill, • incorporate a drip positioned not less than 5 mm outward from the outer face of the cladding below or not less than 15 mm beyond the inner edge of a masonry sill, and • terminate at the jambs or, where the face of the jambs is not at least flush with the face of the cladding and the sills extend beyond the jambs, incorporate end dams sufficiently high to protect against overflow in wind-driven rain conditions. A wind pressure of 10 Pa can raise water 1 mm. Thus, for example, if a window is exposed to a driving rain wind pressure of 200 Pa, end dams should be at least 20 mm high. Figure A-9.27.3.8.(5) Examples of Configurations of Self-Flashing Sills

Analysis of many sealant joint failures indicates that the majority of failures can be attributed to improper joint preparation and deficient installation of the sealant and various joint components. The following ASTM guidelines describe several aspects that should be considered when applying sealants in unprotected environments to achieve a durable application: • ASTM C1193, “Standard Specification for Use of Joint Sealants", • ASTM C1299, “Standard Guide for Use in Selection of Liquid-Applied Sealants", and • ASTM C1472, “Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width”. The sealant manufacturer’s literature should always be consulted for recommended procedures and materials. Page 262 Appendix A • Volume 2

Exceeds 0.60 kPa. For locations where the 1-in-50 hourly wind pressure is greater than 0.60 kPa, the results of testing fasteners to ASTM D1761, “Standard Test Methods for Mechanical Fasteners in Wood and Wood-Based Materials,” must be obtained from a testing facility or from the insulating concrete form manufacturer to confirm their ultimate strengths for both direct withdrawal and lateral shear. In accordance with limit states design as described in Subsection 4.1.3., the factored resistances of the fastener must be equal to or greater than the factored loads on the fastener at the spacing proposed by the designer. In order to align with the limit states design procedures used to develop Table 9.27.5.4.-B, the factored resistances must be calculated by applying a reduction factor of Φ = 0.35 to the fastener's ultimate strengths, and the factored loads must lie within the area under the line of linear interaction in a diagram that plots the factored lateral shear resistance of the fastener against its factored direct withdrawal resistance.

Where cladding is applied to sheathing that is not suitable for fastening, the fastener length must be increased to maintain the minimum fastener penetration depth into the nail-holding base substrate, as specified in Article 9.27.5.7.

Grooves deeper than that specified may be used in thicker cladding providing they do not reduce the thickness to less than the required thickness minus 1.5 mm. Thus, for Type 1 or 2 cladding, grooves must not reduce the thickness to less than 4.5 mm or 6 mm depending on method of support, or to less than 7.5 mm for Type 5 material.

In using Table 9.27.8.2. to determine the thickness of Grade O-2 OSB cladding, substitute “face orientation” for “face grain” in the column headings.

The minimum thickness of 0.33 mm stated in Sentence 9.27.11.1.(1) refers to the total thickness of the materials, i.e., the combination of the minimum thickness of the base steel (0.29 mm) and the minimum coating thickness required by CSSBI 23M, “Standard for Residential Steel Cladding”. Note that the terms “siding” and “cladding” are often used interchangeably.

Compliance with Sentence 9.27.11.1.(2) and CAN/CGSB-93.2-M, “Prefinished Aluminum Siding, Soffits, and Fascia for Residential Use”, is required for aluminum siding that is installed in horizontal or vertical strips. Compliance with Sentence 9.27.11.1.(3) and CAN/CGSB-93.1-M, “Sheet, Aluminum Alloy, Prefinished, Residential”, is required for aluminum cladding that is installed in large sheets.

“Geometrically defined drainage cavity” (GDDC) refers to the channels, grooves or profiles cut into the insulation backing of an EIFS panel for the purpose of providing a way for water that gets behind the system to drain out. The channels, grooves or profiles of one panel need to connect to the channels, grooves or profiles of adjacent panels in order for drainage to occur consistently and uniformly across the entire EIFS. While the size of a channel, groove or profile can be verified by inspecting a single panel, the intent of Sentence 9.27.14.1.(1) is that the required drainage capacity be achieved across the entire system. Additional information on the design and installation of EIFS can be found in • the EIFS Practice Manual published by the EIFS Council of Canada, and • the manufacturer's literature. Appendix A • Volume 2 Page 263 Div. B • A-9.27.14.1.(1) 2012 Building Code Compendium Figure A-9.27.14.1.(1) Geometrically Defined Drainage Cavity

The list of acceptable substrates for each type of EIFS can be found in a system’s respective test report to CAN/ULC-S716.1, “Standard for Exterior Insulation and Finish Systems (EIFS) – Materials and Systems”; however, the following substrates are generally considered acceptable: • minimum 11 mm thick exposure 1 OSB classified as PS2 exterior wall sheathing • minimum 11 mm thick exterior-rated plywood sheathing • minimum 12.7 mm thick exterior gypsum sheathing conforming to ASTM C1177 / C1177M, “Standard Specification for Glass Mat Gypsum Substrate for Use as Sheathing” • cementitious panels • fibre-cement panels • concrete block • clay masonry • cast-in-place concrete Note that, in some cases, the list of acceptable substrates may be limited by the EIFS manufacturer. A-Table 9.28.4.3. Stucco Lath. Paper-backed welded wire lath may also be used on horizontal surfaces provided its characteristics are suitable for such application.

ASTM C840, “Standard Specification for Application and Finishing of Gypsum Board,” specifies requirements for the anchorage of gypsum board panels to flat wall ICF units in the section on System XVI. While the standard practice for the application of gypsum board panels over traditional vertical wood studs or metal framing members is to align the vertical joints of the panels on a supporting member, ASTM C840 requires that the vertical joints between the panels be positioned halfway between the web fastening strips of the flat wall ICF units to minimize damage to the edges of the panels during screw anchorage. The full surface of the flat wall ICF insulation panels (backed by the concrete cores) provide solid, continuous support of the taped gypsum board panel joints, which protects them from potential deflection, cracking and impact damage. Page 264 Appendix A • Volume 2

In some areas of buildings, water and other substances may frequently be splashed or spilled onto the floor. It is preferable, in such areas, that the finish flooring be a type that will not absorb moisture or permit it to pass through; otherwise, both the flooring itself and the subfloor beneath it may deteriorate. Also, particularly in food preparation areas and bathrooms, unsanitary conditions may be created by the absorbed moisture. Where absorbent or permeable flooring materials are used in these areas, they should be installed in such a way that they can be conveniently removed periodically for cleaning or replacement, i.e., they should not be glued or nailed down. Also, if the subfloor is a type that is susceptible to moisture damage (this includes virtually all of the wood-based subfloor materials used in wood frame construction), it should be protected by an impermeable membrane placed between the finish flooring and the subfloor. The minimum degree of impermeability required by Sentence 9.30.1.2.(1) would be provided by such materials as polyethylene, aluminum foil, and most single-ply roofing membranes (EPDM, PVC).

Figure A-9.31.6.2.(3) Securement of Service Water Heater Using Strapping Fastened to Floor Joists Overhead

Containing a Secondary Suite. Ventilation for Smoke Control The control of smoke transfer between dwelling units in a house with a secondary suite, or between the dwelling units and other spaces in the house, is a critical safety issue. Although providing a second ventilation system to serve the two dwelling units is expensive—and potentially difficult in an existing building—it is necessary to achieving a minimum acceptable level of fire safety. Appendix A • Volume 2 Page 265 Alternative solutions to providing separate ventilation systems for the dwelling units must address smoke control. Although smoke dampers restrict the spread of smoke by automatically closing in the event of a fire, their installation in a ventilation system that serves both dwelling units in a house with a secondary suite is not considered to be a workable solution because they are very expensive, require regular inspection and maintenance, and must be reset after every activation. Ventilation for Air Exchange The provision of a ventilation system for the purpose of maintaining acceptable indoor air quality is a critical health issue. However, Sentence 9.32.1.2.(3) allows exits and public corridors in houses with a secondary suite to be unventilated. Lack of active ventilation of these spaces is considered acceptable because occupants do not spend long periods of time there and because exits are somewhat naturally ventilated when doors are opened. Considering the cost of installing separate ventilation systems, Sentence 9.32.1.2.(4) also exempts ancillary spaces in houses with a secondary suite from the requirement to be ventilated, provided that make-up air is supplied in accordance with Article 9.32.3.8.

Sentence 9.32.1.3.(2) applies to the piping and ducting located within the wall assembly and not to the often flexible duct used to connect the appliance to the rigid exhaust vent duct.

For many years, houses were constructed without mechanical ventilation systems. They relied on natural air leakage through the building envelope for winter ventilation. However, houses have become progressively more airtight through the introduction of new products and practices, e.g., the substitution of panel sheathings, such as plywood and waferboard, for board sheathing, the replacement of paper-backed insulation batts with friction-fit batts and polyethylene film, improved caulking materials, and tighter windows and doors. Following the energy crisis in the early 1970s, considerable emphasis was placed on reducing air leakage in order to conserve energy. Electric heating systems were encouraged and higher efficiency furnaces were developed, which further reduced air change rates in buildings. This led to concern that the natural air change in dwelling units might be insufficient in some instances to provide adequate indoor air quality. Condensation problems resulting from higher humidity levels were also a concern. Current Requirements The current requirements for ventilation systems described herein include the following goals: • provisions that are easier to understand, • reduced probability that outdoor air distributed through a forced-air heating system will be cool enough to cause premature deterioration of the furnace heat exchanger, and • reduced probability that the ventilation system will cause excessive depressurization of the dwelling unit. To some extent, the first of these goals conflicts with the other two and its achievement has suffered accordingly. Only in the manner of determining the capacity of the principal ventilation fan [see Sentence 9.32.3.3.(2)] has any significant simplification been achieved. See also Note A-9.32.3.3.(2). Page 266 Appendix A • Volume 2

Performance Approach [Clause 9.32.3.1.(1)(a)] CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems”, is a comprehensive performance standard. It gives experienced ventilation system designers the flexibility to design a variety of residential ventilation systems that satisfy those requirements. Prescriptive Approach [Clause 9.32.3.1.(1)(b)] The prescriptively described systems are intended to provide a level of performance approaching that provided by systems complying with CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems”. They are included in the NBC for use by those less experienced in ventilation system design. Code users who do not find these prescriptively described systems satisfactory for their purposes, or who find them too restrictive, are free to use any other type of ventilation system that satisfies the performance requirements of CAN/CSA-F326-M.

The principal ventilation system circulates air throughout the house for the purpose of maintaining acceptable indoor air quality. Each ventilation system has three main components: • indoor air exhaust • outdoor air supply • distribution of air Indoor Air Exhaust The principal ventilation fan extracts indoor air. Its operation is linked with a means of introducing and distributing outdoor air to the dwelling unit at approximately the same rate at which the indoor air is exhausted, except as permitted by Article 9.32.3.6. The principal ventilation fan must be capable of drawing air from throughout the dwelling unit and exhausting it to the outdoors. Though actual usage will be determined by the occupants, the fan must be capable of continuous operation. Unfortunately, there is no standard method of testing and designating fans for continuous use. Therefore, such a designation is not a mandatory requirement. See Sentence 9.32.3.3.(4)) Supplemental exhaust fans, such as kitchen cooktop hoods and bathroom fans, provide more ventilation at point of source when needed. (See Article 9.32.3.7. and Note A-9.32.3.7.) Outdoor Air Supply Outdoor air is brought into a house either through a supply duct in the exterior wall or, in exhaust-only systems, by leaks through the building envelope. (See also Note A-9.32.3.6.) Distribution of Air( There are two approaches to ensuring air is distributed to all parts of the house: • in forced air heating systems, the furnace circulation fan moves the air through heating distribution ducts , (See Note A- 9.32.3.4.) • in non-forced air heating systems, a supply fan circulates air through dedicated ventilation distribution ducts. (See Note A-9.32.3.5.) Figures A-9.32.3.3.-A to A-9.32.3.3.-F and A-9.32.3.6. show possible configurations of principal ventilation systems. However, even within these prescriptive solutions, a significant degree of flexibility is available. The configurations illustrated should therefore not be regarded as the only configurations acceptable under Sentence 9.32.3.1.(2). Appendix A • Volume 2 Page 267 Figure A-9.32.3.3.-A Possible Configuration of a Mechanical Ventilation System Coupled With a Forced Air Heating System Notes to Figure A-9.32.3.3.-A: (1) The outdoor air supply duct shall be connected not less than 3 m upstream of the plenum connection to the furnace. Page 268 Appendix A • Volume 2 Figure A-9.32.3.3.-B Possible Configuration of a Mechanical Ventilation System Using a Heat Recovery Ventilator Coupled With a Forced Air Heating System Notes to Figure A-9.32.3.3.-B: (1) The outdoor air supply duct shall be connected not less than 3 m upstream of the plenum connection to the furnace. (2) The HRV supply inlet and exhaust outlet shall be separated by a distance of not less than 900 mm. Appendix A • Volume 2 Page 269 Figure A-9.32.3.3.-C Possible Configuration of a Mechanical Ventilation System Not Coupled With a Forced Air Heating System Note to Figure A-9.32.3.3.-C: (1) The outdoor air supply duct shall be connected not less than 3 m upstream of the plenum connection to the furnace. Page 270 Appendix A • Volume 2 Figure A-9.32.3.3.-D Possible Configuration of a Mechanical Ventilation System Using a Heat Recovery Ventilator not Coupled With a Forced Air Heating System Note to Figure A-9.32.3.3.-D: (1) The HRV supply inlet and exhaust outlet shall be separated by a distance of not less than 900 mm. Appendix A • Volume 2 Page 271 Figure A-9.32.3.3.-E Ventilation System Coupled With a Forced Air Heating System and Using a Dual-Capacity Principal Ventilation Fan to Eliminate the Need for Supplemental Fans Notes to Figure A-9.32.3.3.-E: (1) The make-up air fan operates when the PVF operates at 2.5 times the required capacity. (2) The outdoor air supply duct shall be connected not less than 3 m upstream of the plenum connection to the furnace. Page 272 Appendix A • Volume 2 Figure A-9.32.3.3.-F Ventilation System Coupled With a Forced Air Heating System and Using a Heat Recovery Ventilator as the Principal Ventilation Fan to Eliminate the Need for Supplemental Fans Notes to Figure A-9.32.3.3.-F: (1) The outdoor air supply duct shall be connected not less than 3 m upstream of the plenum connection to the furnace. (2) The HRV supply inlet and exhaust outlet shall be separated by a distance of not less than 900 mm. Appendix A • Volume 2 Page 273

The principal ventilation fan operates at a rate known as the “normal operating exhaust capacity”. This rate is intended to be suitable for use on a continuous basis at any time that an ongoing, background level of ventilation is needed, e.g. the late fall or early spring when air leakage driven by wind and inside/outside temperature differences is lowest but it is too cold to rely on open windows. The capacity of the principal ventilation fan is determined on the basis of the number of bedrooms in the house rather than on the basis of some fraction of the house volume, as in previous editions of the Building Code. This is because the amount of ventilation required is related to the activities of people, and the number of people in the house is usually related to the number of bedrooms rather than to the size of the house. It should be emphasized that this air change rate refers to the installed capacity of the system, not to the rate of ventilation that is actually used in the house. In many households, ventilating even at the background rate would provide more ventilation than required, resulting in unnecessarily high heating bills and perhaps excessively low indoor relative humidity. Thus, although a system with the minimum capacity must be installed, it can incorporate controls that allow the system to be used at less than its full capacity most of the time. A maximum is set for the capacity of the principal ventilation fan because, if it were to be much larger than the ventilation needs of the household, it might never be used. The principal ventilation fan is intended to provide a relatively low level of ventilation such that it can be run continuously without too much noise and without serious energy penalty. If the installed capacity exceeds the minimum by a large margin and the fan flow cannot be reduced, there is increased probability that the fan will not be used at all, thus defeating the purpose of having it in the first place. Sentence 9.32.3.3.(2) therefore places limits on oversizing.

The principal ventilation fan must incorporate controls that allow it to be turned off. There are four main types of controls used in residential applications: (a) Manual on-off switch: This is the simplest form of control but, while acceptable, it is not the best means of maintaining indoor air quality. Occupants may turn the system off and forget to turn it back on, or may turn it off to save on heating bills or to reduce noise, not realizing the importance of proper ventilation. (b) Dehumidistat: A dehumidistat automatically activates the ventilation system in response to rising humidity. Humidity is often the main reason why ventilation is required, but not always. Depending on the activities of the occupants and the relative strengths of other sources of pollutants and humidity, the amount of ventilation required to control humidity may not be enough to control other pollutants. (c) Carbon Dioxide Sensor: Ventilation systems in large buildings are sometimes controlled by carbon dioxide (CO2) sensors and this technology is just beginning to be available on a residential scale. Increasing CO2 concentration is usually a good indication of decreasing air quality. But even this form of control may not be satisfactory in cases where there are unusual pollutants, such as those generated by certain hobbies. (d) Periodic Cycling Control: Devices are available that cause the furnace circulation fan to operate at user-set intervals if the thermostat does not call for heat. If such a device were wired so that it turns on the principal ventilation fan as well as the furnace circulation fan, it would satisfy the requirements of Article 9.32.3.4. However, if it were wired to only operate the furnace circulation fan in a system designed to Article 9.32.3.4., at times the principal ventilation fan would operate without the furnace circulation fan. Since such systems rely on the furnace circulation fan drawing in outdoor air to balance the exhaust flow through the principal ventilation fan, this would result in the exhaust flow not being balanced and the dwelling being depressurized. This configuration would therefore not be acceptable. This device would be acceptable in conjunction with a system designed in accordance with Article 9.32.3.6. Page 274 Appendix A • Volume 2

The intent of the requirement to locate the controls in the living area is to have them easily accessible to the occupants, rather than in a little used room or unfinished basement, for example. Installers should consider marking the manual switch with an icon depicting a fan as well as the words “Ventilation Fan.”

Where the kitchen or a bathroom is chosen as the location for the air intake of the principal ventilation fan, the intake must be positioned high enough to capture contaminants, warm moist air, and hot gases, which tend to rise and stratify near the ceiling. These restrictions prevent the use of a cooktop exhaust or hood fan as the principal ventilation fan.

Systems. Coupling a ventilation system with a forced air heating system to provide the necessary distribution of outdoor air is relatively simple. A duct brings air from outdoors to the heating system's return air plenum. Whenever the principal ventilation fan is activated, the furnace fan is automatically activated to distribute the outdoor air. (See Sentence 9.32.3.4.(9)) Where no auxiliary supply fan is installed as per Sentence 9.32.3.4.(8), the furnace fan also drives the flow of outdoor air in through the outdoor air duct. Use of an auxiliary supply fan allows the size of the outdoor air supply duct to be reduced. This system tempers the outdoor air before it reaches occupied areas of the house by mixing it with return air in the furnace's return air plenum. It is important that thorough mixing occur before the cold air reaches the furnace's heat exchanger, otherwise condensation could reduce the service life of the heat exchanger. The 3 m minimum distance between the furnace and the outdoor air duct connection is one means of addressing this concern. However, a well-designed mixing device is likely to be more effective, as are certain arrangements of the outdoor air duct's connection to the return air plenum. Figures A-9.32.3.4.-A and A-9.32.3.4.-B illustrate one such device and arrangements that have been shown to be effective in research carried out by Canada Mortgage and Housing Corporation (“Testing of Fresh Air Mixing Devices,” IRTA Research for Research Division of CMHC, March 1993). Figure A-9.32.3.4.-A Simple Air Mixing Device Appendix A • Volume 2 Page 275 Figure A-9.32.3.4.-B Connection of Outdoor Air Duct to Return Air Plenum Even if the outdoor air is well mixed with the return air, in very cold weather the resulting mixed air temperature could still be lower than what the furnace heat exchanger can tolerate if there is too much outdoor air. That is why Article 9.32.3.4. includes several provisions, including Table 9.32.3.4. and the requirement to actually measure the outdoor airflow (see Sentence 9.32.3.4.(10)), to guard against this possibility. In some cases, it will not be possible to use the forced air heating system to circulate the outdoor air unless additional heating devices are used to temper the outdoor air before it reaches the furnace heat exchanger. This would be the case, for example, in a highly insulated house with a small furnace that is located in a very cold region. The maximum outdoor airflow permitted by Table 9.32.3.4. must equal or exceed the “normal operating exhaust capacity” of the principal ventilation fan, as determined in accordance with Sentence 9.32.3.3.(2); otherwise there is an increased possibility that the mixed airflow over the furnace heat exchanger in cold weather will be colder than what the heat exchanger can tolerate. No values are listed in Table 9.32.3.4. when the maximum flow permitted exceeds the maximum capacity found in Table 9.32.3.3. since no higher outdoor airflow is required to match the flow of the principal ventilation fan. Sentence 9.32.3.3.(9) is intended to avoid having the principal ventilation fan exhaust the outdoor air brought in through the outdoor air supply duct before it is circulated to the dwelling. The design of some advanced integrated mechanical systems is such that some portion of the outdoor air is exhausted before being circulated but this is taken into account in the design of the system and the total amount of outdoor air brought in is adjusted accordingly. This provision is not intended to preclude the use of such systems. The duct bringing outdoor air to the furnace return air plenum must be equipped with a manual damper [see Sentence 9.32.3.4.(6)] that is adjusted (see Sentence 9.32.3.4.(10)) to balance the outdoor airflow with the flow through the principal ventilation fan. It is recommended, but not mandatory, that a motorized damper also be installed in this duct and that it be wired to be fully open when the principal ventilation fan is operating and fully closed when the principal ventilation fan is not operating. This damper will allow ventilation to occur only when the occupants have called for it by turning the “Ventilation Fan” switch to “on.” The absence of such a damper can lead to unwanted ventilation, which can result, in turn, in excessive dryness and increased heating costs in winter, and increased loading on air-conditioning equipment in the summer. Page 276 Appendix A • Volume 2

Systems. If there is no forced air heating system or if, for some reason, the heating system is not used to distribute the outdoor air, then a special air distribution system must be installed. Because such a system only handles ventilation air and not heating distribution air, smaller ducts can generally be used and the supply fan is quite a bit smaller than a normal furnace circulation fan. Sentences 9.32.3.5.(2) to (7) require that the supply fan operate at the same time and at the same rate as the principal ventilation fan in order to avoid either pressurizing or depressurizing the house. Pressurizing the house can lead to interstitial condensation within the building envelope. Depressurization can lead to the spillage of combustion products from heating equipment and increased entry of soil gas. Tempering of Outdoor Air The system described in Article 9.32.3.5. requires that the outdoor air be tempered before being circulated to the occupied areas of the house (see Sentence 9.32.3.5.(8)). Tempering can be accomplished by passing the outdoor air over some type of heating element or by mixing it with indoor air. However, the latter approach is more complex, since it requires that the ratio between the outdoor air and indoor air ducts or openings be neither too large nor too small. It was judged to be too complex to include within the context of these prescriptive requirements. Therefore, where tempering by mixing with indoor air is chosen, the system must be designed in accordance with CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems.” Distribution of Outdoor Air Whereas a duct system associated with a forced air heating system would have ducts leading to almost all rooms, the requirements for these ventilation systems are more limited (see Sentences 9.32.3.5.(10) to (14)). The most important point is that outdoor air must be provided to each bedroom; people often spend long periods of time in the bedroom with the door closed. It is also required that at least one duct lead to every storey, including the basement. In houses where there is no storey without a bedroom (e.g. bungalows with no basement), a duct must lead to the principal living area. Where there is more than one area that could be considered as a “living area,” at least one such area must be designated as the “principal living area.” There is also the alternative of locating one of the exhaust air intakes for the principal ventilation fan in the principal living area, rather than supplying outdoor air directly to it; in this arrangement, the outdoor air will pass through the principal living area on its way to the exhaust fan. However, this arrangement will be less effective if only a small portion of the exhaust is withdrawn from the principal living area; thus, there is a limitation on the number of other exhaust air intakes for the principal ventilation fan. (See Sentence 9.32.3.5.(11))].

If a house does not incorporate any provision for the introduction of outdoor air, the air extracted by the principal ventilation fan will be replaced by outdoor air leaking in through the building envelope. The house will be depressurized by operation of the principal ventilation fan, and the negative internal pressure will draw outdoor air inside through any available opening. See Figure A-9.32.3.6. This need not be of concern if the house also does not incorporate any spillage-susceptible combustion equipment. Such a system is significantly simpler in that the concern about too-cold air contacting the furnace heat exchanger is eliminated. However, in an exhaust-only system there is no control over where the outdoor air enters; e.g., the majority of envelope leaks could be into an infrequently occupied basement. Thus, it is required that houses using this system have an air distribution system so that, no matter where the outdoor air comes in, it will be mixed with the indoor air and circulated throughout the house. A forced air heating system complying with Section 9.33. satisfies the criteria for the air distribution system in Clause 9.32.3.6.(1)(b). In a house with a very airtight building envelope, it may be difficult for the principal ventilation fan to achieve its full rated flow capacity due to high levels of house depressurization. Therefore, fans used as the principal ventilation fan in an exhaust-only ventilation system are required to have their flow rated at a higher static pressure (See Sentence 9.32.3.10.(3)) See Figure A-9.32.3.6. Appendix A • Volume 2 Page 277 Figure A-9.32.3.6. Possible Configuration of an Exhaust-Only Ventilation System Coupled With a Forced Air Heating System

CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems,” requires a certain amount of exhaust from kitchens to capture pollutants at the source. When the principal ventilation fan air intake is not located in the kitchen, a separate kitchen exhaust fan must be installed [see Sentence 9.32.3.7.(1)]. However, when the principal ventilation fan is located in the kitchen but is connected to multiple inlets, there will not be enough exhaust from the kitchen. Therefore, a separate kitchen exhaust fan is required in this circumstance as well, unless the exhaust rate of the principal ventilation fan can be increased when additional kitchen ventilation is needed. (See Sentence 9.32.3.7.(3)) The bathroom is another possible location for an air intake of a principal ventilation fan. As with the kitchen, if this option is not chosen, a separate bathroom exhaust fan must be installed. (See Sentence 9.32.3.7.(4)) Supplemental exhaust fans, which in most instances are located in kitchens and bathrooms, are required to be coupled to supply fans of similar capacity. The make-up air is necessary so that operation of the supplementary exhaust fan(s) will not depressurize the house. (See Sentence 9.32.3.8.(2)) See also Note A-9.32.3.8. Page 278 Appendix A • Volume 2

When an exhaust device extracts air from a house and there are no provisions for the introduction of outdoor air, such as by means of an outdoor air duct as required by Articles 9.32.3.4. and 9.32.3.5., and no supply fans are operating simultaneously, the exhausted air will automatically be replaced by outdoor air that has infiltrated through the house's building envelope. The rate of inward leakage will automatically equal the rate of outward extraction: otherwise the house would eventually implode. The instant the exhaust device is turned on, the house pressure is lowered and the inside/outside pressure difference drives outdoor air in through any leaks it can find. See Figure A-9.32.3.8.-A. Figure A-9.32.3.8.-A Outdoor Air Drawn Through a Leaky Envelope Even if the house is made more airtight, the inward leakage will equal the outward fan flow. However, because there are fewer and/or smaller leakage sites in an airtight house, it will take a larger inside/outside pressure difference to drive the same amount of air through the remaining leakage sites. See Figure A-9.32.3.8.-B. Appendix A • Volume 2 Page 279 Figure A-9.32.3.8.-B Outdoor Air Drawn Through a Tighter Envelope It is possible that the exhaust device will no longer be able to achieve its rated flow when operating against a very high inside/outside pressure difference. However, in this case, the inward flow will also decrease and will still be in equilibrium with the outward flow, but now at a higher inside/outside pressure difference than in a leakier house. An exhaust device not operated in conjunction with a supply fan will always depressurize a house to some extent—even a leaky house. But it will depressurize a tight house more than it will depressurize a leaky house. And, of course, an exhaust device with a higher capacity will depressurize a house more than a device with a smaller capacity. Spillage of Combustion Products Depressurization of the house by the ventilation system or other exhaust devices can cause the spillage of combustion products from certain types of combustion appliances. The types of appliances that are susceptible to pressure-induced spillage can generally be identified by the fact that they are vented through a natural draft chimney rather than through an arrangement that uses a fan to draw the products of combustion out of the house. Naturally aspirated gas furnaces with draft hoods and oil furnaces with barometric dampers are examples of spillage-susceptible appliances. Page 280 Appendix A • Volume 2 On the other hand, some gas furnaces with induced draft venting systems and the “sealed combustion” oil furnaces commonly used in mobile homes, are more resistant to spillage. Terms used in gas appliance standards to describe categories of spillage-resistant appliances include “direct-vented” and “side-wall-vented.” Almost all fireplaces are spillage-susceptible, even those with so called “airtight” glass doors and outside combustion air intakes, since most “airtight” doors are not really airtight. Certain types of gas combustion appliances, such as cooking appliances and “decorative appliances,” are not required to be vented. Their operation will not be significantly affected by depressurization of the house. The Building Code addresses the potential for spillage from combustion appliances with requirements for: • makeup air, and • carbon monoxide alarms. Makeup Air Requirements Depressurization caused by the principal ventilation system itself is not an issue in houses with balanced systems (that is, non-exhaust-only systems). However, the operation of other exhaust devices, such as stove-top barbecues, can cause depressurization. Therefore, in a house with spillage-susceptible appliances, any such exhaust devices, including the required supplemental exhaust fans, must be provided with makeup air. (See Sentence 9.32.3.8.(2)) In the past, the NBC and other codes and standards have tended to rely on the passive supply of makeup air through makeup air openings. This is no longer considered to be a reliable approach in the context of a simple, prescriptively described system without sophisticated controls on depressurization. Therefore, the makeup air must be provided by a supply fan that is automatically activated whenever the exhaust device that requires the makeup air is activated. (See Sentences 9.32.3.8.(2) and (3)) The need for makeup air can be avoided by not using spillage-susceptible combustion equipment. Carbon Monoxide Alarm Requirements for Solid-Fuel-Burning Appliances Even at a relatively low level of depressurization, certain open-type solid-fuel-burning appliances, such as fireplaces, or even closed-type solid-fuel-burning appliances whose stoking doors are left open, can spill products of combustion into the house when operating in their “die down” or smouldering stages. In the absence of more sophisticated design and installation controls to prevent such levels of depressurization (such as those mentioned in CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems,” the only available safeguard is to require the installation of a carbon monoxide (CO) alarm in any room incorporating a solid-fuel-burning device. (See Sentence 9.32.3.9.(3)) Where this is not acceptable, the prescriptively described alternatives must be abandoned and a system fully complying with CAN/CSA-F326-M must be designed. One advantage of solid-fuel-burning devices is that their spillage is readily detected by a carbon monoxide alarm (which is not true of gas- or oil-burning devices). Therefore, where this is the only type of spillage-susceptible combustion device present, one has the choice of not providing makeup air for exhaust devices ([see Sentence 9.32.3.8.(6)): the carbon monoxide alarm required by Sentence 9.32.3.9.(3) will warn occupants when depressurization is causing spillage. Battery-operated carbon monoxide alarms are permitted, but they must be mechanically fixed to a surface. See also Note A-9.32.3.9.

Carbon monoxide (CO) is a colourless, odourless gas that can build up to lethal concentrations in an enclosed space without the occupants being aware of it. Thus, where an enclosed space incorporates or is near a potential source of CO, it is prudent to provide some means of detecting its presence. Dwelling units have two common potential sources of CO: • fuel-fired space- or water-heating equipment within the dwelling unit or in adjacent spaces within the building, and • attached storage garages. Appendix A • Volume 2 Page 281 Most fuel-fired heating appliances do not normally produce CO and, even if they do, it is normally conveyed outside the building by the appliance's venting system. Nevertheless, appliances can malfunction and venting systems can fail. Therefore, the provision of appropriately placed CO alarms in the dwelling unit is a relatively low-cost back-up safety measure. Similarly, although Article 9.10.9.18. requires that the walls and floor/ceiling assemblies separating attached garages from dwelling units incorporate an air barrier system, there have been several instances of CO from garages being drawn into houses, which indicates that a fully gas-tight barrier is difficult to achieve. The likelihood of preventing the entry of all CO is decreased if the dwelling unit is depressurized in relation to the garage. This can readily occur due to the operation of exhaust equipment or simply due to the stack effect created by heating the dwelling unit. Again, CO alarms in the dwelling unit provide a relatively low-cost back-up safety measure. See also Note A-9.32.3.8.

The principal ventilation fan is intended to be run for long periods. Even the supplemental exhaust fans may be used for significant periods. Therefore, all fans that are mounted such that their sound is likely to intrude on the household, other than kitchen exhaust fans, are required to have reasonably low sound ratings so that building occupants will not turn them off before the need for ventilation has been met.

Table 9.32.3.11.-A is based on the data listed in Table 9, “Friction Chart for Round Ducts,” Chapter 32, of the ASHRAE 1997, “ASHRAE Handbook – Fundamentals.” The allowable duct lengths listed in the Table have been calculated assuming the “equivalent lengths” of ducts are four times their physical lengths. The static pressure offset to account for building pressures is 10 Pa. Using Table 9.32.3.11.-A will generally result in very conservatively sized (i.e. larger) ducts compared to what would be achieved using the normal duct design procedures referenced in Subsection 9.33.4.

Enthalpy recovery ventilators (ERVs) are a type of heat recovery ventilator and must therefore comply with the requirements of Article 9.32.3.12.

The operation of an air exhaust system or of a fuel-burning appliance removes the air from a house, creating a slight negative pressure inside. In certain cases the natural flow of air up a chimney can be reversed, leading to a possible danger of carbon monoxide poisoning for the inhabitants. Newer houses are generally more tightly constructed than older ones because of improved construction practices, including tighter windows, weather stripping and caulking. This fact increases the probability that infiltration may not be able to supply enough air to compensate for simultaneous operation of exhaust fans, fireplaces, clothes dryers, furnaces and space heaters. It is necessary, therefore, to introduce outside air to the space containing the fuel-burning appliance. Information regarding combustion air requirements for various types of appliances can be found in the installation standards referenced in Articles 6.2.1.4. and 9.33.1.2. In the case of solid-fuel burning stoves, ranges and space heaters, CAN/CSA-B365, “Installation Code for Solid-Fuel-Burning Appliances and Equipment” suggests that the minimum size of openings be determined by trial and error to accommodate the flue characteristics, the firing rate, the building characteristics, etc., and that, as a guide, the combustion air opening should be 0.5 times the flue collar area. Further information is available in Canadian Building Digest 222, “Airtight Houses and Carbon Monoxide Poisoning”, from the Institute for Research in Construction, National Research Council of Canada, Ottawa K1A 0R6. Page 282 Appendix A • Volume 2

Where a single heating system serves two dwelling units and common spaces a house with a secondary suite, it must be possible for the occupants to control the temperature in their own suites. Sentence 9.33.4.3.(1), which applies only to electric, fuel-fired or unitary heaters and hydronic heating systems, specifies that separate temperature controls must be provided in each dwelling unit in a house with a secondary suite; however, the controls for shared spaces may be located in those spaces or in one of the suites.

Burning Appliances. CSA B365, “Installation Code for Solid-Fuel-Burning Appliances and Equipment” is essentially an installation standard, and covers such issues as accessibility, air for combustion and ventilation, chimney and venting, mounting and floor protection, wall and ceiling clearances, installation of ducts, pipes, thimbles and manifolds, and control and safety devices. But the standard also includes a requirement that solid-fuel-burning appliances and equipment satisfy the requirements of one of a series of standards, depending on the appliance or equipment, therefore also making it a design and construction standard. It is required that stoves, ranges, central furnaces and other space heaters be designed and built in conformity with the relevant referenced standard.

CSA B415.1-10 and the US EPA Standard cover appliances that burn biomass fuels other than coal and require appliances equipped with catalytic combustors have an average particulate emission rate ≤ 2.5 g/h and appliances not equipped with catalytic combustors have an average particulate emission rate ≤ 4.5 g/h. Both CSA and EPA test particulate emissions using the same testing methods. These standards do not cover site-built masonry fireplaces or site-built masonry heaters. They do not apply to factory-built fireplaces with a minimum burn rate ≥ 5 kg/h.

It is a common practice to introduce outdoor air to the house by means of an outdoor air duct connected to the return air plenum of a forced air furnace. This is an effective method and is a component of one method of satisfying the mechanical ventilation requirements of Subsection 9.32.3. However, some caution is required. If the proportion of cold outside to warm return air is too high, the resulting mixed air temperature could lead to excessive condensation in the furnace heat exchanger and possible premature failure of the heat exchanger. CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems,” requires that this mixed air temperature not be below 15.5°C when the outdoor temperature is at the January 2.5% value. It is also important that the outdoor air and the return air mix thoroughly before reaching the heat exchanger. Note A-9.32.3. provides some guidance on this.

Under the provisions of Article 1.2.1.1. of Division A, certain solid-fuel-burning appliances may be connected to factory- built chimneys other than those specified in Sentence 9.33.10.2.(1) if tests show that the use of such a chimney will provide an equivalent level of safety.

Design Assumptions: 1. Density of Reinforced Concrete = 23.5 kN/m3. 2. Live Loads - As per Sentence 9.4.2.3 (1) of the Building Code, the live load is the lesser of the following: • 1.9 kPa, • Specified roof snow load, which for Ontario is up to 2.9 kPa. Therefore a specified design load of 3.0 kPa is appropriate; however, the slab specified is capable of carrying higher live loads since the crack control requirements of CSA A23.3 and cover requirements as given below govern the design of the slab. 3. Design Standards: CSA A23.3-94, “Design of Concrete Structures”. Appendix A • Volume 2 Page 283 4. Exposure and Cover for Reinforcing Steel: • The slab is considered to be exposed to weather and de-icing chemicals. • Minimum top cover is 60 mm as per CSA A23.3 Clause A15.1.7.1 plus a 12 mm tolerance on placement. • Minimum bottom cover is 30 mm as per CSA A23.3 Clause A12.6.2 (slab cast against formwork). • For 10M reinforcing bars the minimum slab thickness is 72 mm cover + 11.3 mm bar + 11.3 mm bar + 30 mm cover = 125 mm. 5. Design Assumptions: • Concrete compressive strength of 32 MPa at 28 days as per Sentence 9.3.1.6.(1) of the Building Code. • Reinforcing steel yield strength of 400 MPa. • Slab design is based on a one-way slab simply supported on foundation walls along the edges. Since the slab can be square or rectangular, the same steel is provided in both directions. • Maximum span is limited to 20 times the slab thickness as per CSA A23.3 Table 9.1.