OBC VOLUME 2 · SUPPLEMENTARY STANDARD SB-2Updated for the 2024 Ontario Building Code
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SB-2 — Fire Performance Ratings
Supplementary Standard SB-2 ("Fire Performance Ratings") forms part of Volume 2 of the 2024 Ontario Building Code. The full text is reproduced below with a linked table of contents.
On this page:
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2024MMAH Supplementary Standard SB-2
SB-2 Fire-Performance Ratings
Section 1 General
This Supplementary Standard is based in large measure on Appendix D of the National Building Code of Canada 2020.
The content of Appendix D was prepared on the recommendations of the Standing Committee on Fire Performance
Ratings, which was established by the Canadian Commission on Building and Fire Codes (CCBFC) for this purpose.
1.1.1.Scope
(1) This fire-performance information is presented in a form closely linked to the performance requirements and the
minimum materials specifications of the 2024 Building Code.
(2) The ratings have been assigned only after careful consideration of all available literature on assemblies of common
building materials, where they are adequately identified by description. The assigned values based on this information
will, in most instances, be conservative when compared to the ratings determined on the basis of actual tests on individual
assemblies.
(3) The fire-performance information set out in this Supplementary Standard applies to materials and assemblies of
materials which comply in all essential details with the minimum structural design standards described in Part 4 of
Division B in the 2024 Building Code. Additional requirements, where appropriate, are described in other Sections of
this Supplementary Standard.
(4) Section 2 of this Supplementary Standard assigns fire-resistance ratings for walls, floors, roofs, columns and beams
related to CAN/ULC-S101, "Standard Method of Fire Endurance Tests of Building Construction and Materials", and
describes methods for determining these ratings.
(5) Section 3 assigns flame-spread ratings and smoke developed classifications for surface materials related to
CAN/ULC-S102, "Standard Method of Test for Surface Burning Characteristics of Building Materials and Assemblies"
and CAN/ULC-S102.2, "Standard Method of Test for Surface Burning Characteristics of Flooring, Floor Coverings, and
Miscellaneous Materials and Assemblies".
(6) Section 4 describes noncombustibility in building materials when tested in accordance with CAN/ULC-S114,
"Standard Method of Test for Determination of Non-Combustibility in Building Materials".
(7) Section 5 contains requirements for the installation of fire doors and fire dampers in fire-rated stud wall assemblies.
(8) Section 6 contains construction specifications for exterior wall assemblies that are deemed to satisfy the criteria of
Clause 3.1.5.5.(1)(b) when tested in accordance with CAN/ULC-S134, “Standard Method of Fire Test of Exterior Wall
Assemblies”.
(9) Section 7 contains background information regarding fire test reports, obsolete materials and assemblies, assessment
of archaic assemblies and the development of the component additive method.
1.1.2.Referenced Documents
(1) Where documents are referenced in this Supplementary Standard, they shall be the editions designated in
Table 1.1.2.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 1.1.2.
Documents Referenced in SB-2 Fire-Performance Ratings(1)
Issuing
Document Number Title of Document Reference
Agency
ANSI A208.1-2009 Particleboard Table 3.1.1.A.
Standard Specification for Lightweight Aggregates for Structural
ASTM C330 / C330M-17 1.4.3.(2)
Concrete
Standard Specification for Application and Finishing of Gypsum
ASTM C840-18b 2.3.9.(1)
Board
1.5.1.(1); 1.5.1.(2)
ASTM C1396 / C1396M-17 Standard Specification for Gypsum Board
Table 3.1.1.A.
Standard Practice for Accelerated Weathering of Fire-Retardant-
ASTM D2898-10 6.1.1.
Treated Wood for Fire Testing
CCBFC NRCC 30629 Supplement to the National Building Code of Canada 1990 7.2.; 7.3.
CGSB 4-GP-36M-1978 Carpet Underlay, Fibre Type Table 3.1.1.B.
CGSB CAN/CGSB-4.129-97 Carpets for Commercial Use Table 3.1.1.B.
CGSB CAN/CGSB-92.2-M90 Trowel or Spray Applied Acoustical Material 2.3.4.(5)
Concrete materials and methods of concrete construction / Test
CSA A23.1:19 / A23.2:19 1.4.3.(1)
methods and standard practices for concrete
2.1.5.(2); 2.6.6.(1)
CSA A23.3:19 Design of concrete structures Table 2.6.6.B.
2.8.2.(1); Table 2.8.2.
CSA CAN/CSA-A82:14 Fired masonry brick made from clay or shale Table 2.6.1.A.
CSA A82.22-M1977 Gypsum Plasters Table 3.1.1.A.
CAN/CSA-A82.27- 1.5.1.(1); 1.5.1.(2)
CSA Gypsum Board
M91 Table 3.1.1.A.
1.7.2.(1); 2.3.9.(1)
CSA A82.30-M1980 Interior Furring, Lathing and Gypsum Plastering
Table 2.5.1.
CSA A165.1-14 Concrete block masonry units Table 2.1.1.
CSA O86:19 Engineering design in wood 2.11.3.; 2.11.4.
Evaluation of Adhesives for Structural Wood Products (Limited
CSA O112.10-08 2.3.6.(4)
Moisture Exposure)
CSA O121-17 Douglas fir plywood Table 3.1.1.A.
CSA O141:05 Softwood lumber 2.3.6.(2); Table 2.4.1.
CSA O151:17 Canadian softwood plywood Table 3.1.1.A.
CSA O153-13 Poplar plywood Table 3.1.1.A.
CSA O325-16 Construction sheathing Table 3.1.1.A.
CSA O437.0-93 OSB and Waferboard Table 3.1.1.A.
2.6.6.(1); 2.6.6.(3)
CSA S16:19 Design of steel structures
Table 2.6.6.B.
Column 1 2 3 4
Page 2 • SB-2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 1.1.2. (Cont’d)
Documents Referenced in SB-2 Fire-Performance Ratings(1)
Issuing
Document Number Title of Document Code Reference
Agency
NFPA 80-2013 Standard for Fire Doors and Other Opening Protectives 5.2.1.(1); 5.2.1.(2)
Standard Method of Fire Endurance Tests of Building 1.1.1.(4); 1.12.1.
ULC CAN/ULC-S101-14
Construction and Materials 2.3.2.; 2.11.1.
Standard Method of Test for Surface Burning Characteristics of
ULC CAN/ULC-S102-10 1.1.1.(5); 6.1.1.
Building Materials and Assemblies
Standard Method of Test for Surface Burning Characteristics of
1.1.1.(5)
ULC CAN/ULC-S102.2:2018 Flooring, Floor Coverings, and Miscellaneous Materials and
Table 3.1.1.B.
Assemblies
ULC CAN/ULC-S112.2-07 Standard Method of Fire Test of Ceiling Firestop Flap Assemblies 2.3.10.; 2.3.11.
Standard Method of Test for Determination of Non-Combustibility 1.1.1.(6)
ULC CAN/ULC-S114:2018
in Building Materials 4.1.1.; 4.2.1.
ULC CAN/ULC-S134-13 Standard Method of Fire Test of Exterior Wall Assemblies 1.1.1.; 6.1.1.
Table 2.3.4.A.
Standard for Mineral Fibre Thermal Insulation for Buildings, Table 2.3.4.G.
ULC CAN/ULC-S702.1-14
Part 1: Material Specification 2.3.5.(2); 2.3.5.(4)
Table 2.6.1.E.; 6.1.1.; 7.4.
ULC CAN/ULC-S703-09 Standard for Cellulose Fibre Insulation (CFI) for Buildings 2.3.4.(5)
ULC CAN/ULC-S706.1:2016 Standard for Wood Fibre Insulating Boards for Buildings Table 3.1.1.A.
Column 1 2 3 4
Notes to Table 1.3.1.2.:
(1) Some documents may have been reaffirmed or reapproved. Check with the applicable issuing agency for up-to-date information.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
1.1.3.Applicability of Ratings
(1) The ratings shown in this document apply if more specific test values are not available. The construction of an
assembly that is the subject of an individual test report must be followed in all essential details if the fire-resistance rating
reported is to be applied for use with the Building Code.
1.1.4.Higher Ratings
(1) The authority having jurisdiction may allow higher fire-resistance ratings than those derived from this
Supplementary Standard, where supporting evidence justifies a higher rating. Additional information is provided in
summaries of published test information and the reports of fire tests carried out by NRC, which are included in Section 7,
Background Information.
1.1.5.Additional Information on Fire Rated Assemblies
(1) Assemblies containing materials for which there is no nationally recognized standard are not included in this
Supplementary Standard. Many such assemblies have been rated by Underwriters Laboratories (UL), Underwriters'
Laboratories of Canada (ULC) or Intertek Testing Services NA Ltd. (ITS).
1.2.1.Limitations
(1) The fire-performance ratings set out in this Supplementary Standard are based on those that would be obtained from
the standard methods of test described in the Building Code. The test methods are essentially a means of comparing the
performance of one building component or assembly with another in relation to its performance in fire.
(2) Since it is not practicable to measure the fire resistance of constructions in situ, they must be evaluated under some
agreed test conditions. A specified fire-resistance rating is not necessarily the actual time that the assembly would endure
in situ in a building fire, but is that which the particular construction must meet under the specified methods of test.
(3) Considerations arising from departures in use from the conditions established in the standard test methods may, in
some circumstances, have to be taken into account by the designer and the authority having jurisdiction. Some of these
conditions are covered at present by the provisions of the Building Code.
(4) For walls and partitions, the stud spacing previously specified as 16 and 24 inch on centre have been converted to
406 and 610 mm respectively to represent actual stud spacing used in the field to accommodate modular sheathing panel
dimensions. These metric dimensions are deemed to comply with test results based on reported stud spacing of 400 mm
or 600 mm on centre.
1.3.1.Aggregates in Concrete
(1) Low density aggregate concretes generally exhibit better fire performance than natural stone aggregate concretes. A
series of tests on concrete masonry walls, combined with mathematical analysis of the test results, has allowed further
distinctions between certain low density aggregates to be made.
1.4.1.Description
(1) For purposes of this Supplementary Standard, concretes are described as Types S, N, L, L1, L2, L40S, L120S or
L220S as described in Sentences (2) to (8).
(2) Type S concrete is the type in which the coarse aggregate is granite, quartzite, siliceous gravel or other dense
materials containing at least 30% quartz, chert or flint.
(3) Type N concrete is the type in which the coarse aggregate is cinders, broken brick, blast furnace slag, limestone,
calcareous gravel, trap rock, sandstone or similar dense material containing not more than 30% of quartz, chert or flint.
(4) Type L concrete is the type in which all the aggregate is expanded slag, expanded clay, expanded shale or pumice.
(5) Type L1 concrete is the type in which all the aggregate is expanded shale.
(6) Type L2 concrete is the type in which all the aggregate is expanded slag, expanded clay or pumice.
(7) Type L40S concrete is the type in which the fine portion of the aggregate is sand and low density aggregate in which
the sand does not exceed 40% of the total volume of all aggregates in the concrete.
(8) Type L120S and Type L220S concretes are the types in which the fine portion of the aggregate is sand and low
density aggregate in which the sand does not exceed 20% of the total volume of all aggregates in the concrete.
Page 4 • SB-2
1.4.2.Determination of Ratings
(1) Where concretes are described as being of Type S, N, L, L 1 or L2, the rating applies to the concrete containing the
aggregate in the group that provides the least fire resistance. If the nature of an aggregate cannot be determined
accurately enough to place it in one of the groups, the aggregate shall be considered as being in the group that requires a
greater thickness of concrete for the required fire resistance.
1.4.3.Description of Aggregates
(1) The descriptions of the aggregates in Type S and Type N concretes apply to the coarse aggregates only. Coarse
aggregate for this purpose means that retained on a 5 mm sieve using the method of grading aggregates described in
CSA A23.1 / A23.2, "Concrete materials and methods of concrete construction / Test methods and standard practices for
concrete".
(2) Increasing the proportion of sand as fine aggregate in low density concretes requires increased thicknesses of
material to produce equivalent fire-resistance ratings. Low density aggregates for Type L and Types L-S concretes used
in loadbearing components shall conform to ASTM C330 / C330M, "Standard Specification for Lightweight Aggregates
for Structural Concrete".
(3) Non-loadbearing low density components of vermiculite and perlite concrete, in the absence of other test evidence,
shall be rated on the basis of the values shown for Type L concrete.
1.5.1.Types of Gypsum Board
(1) Where the term “gypsum board” is used in this Supplementary Standard, it is intended to include, in addition to
gypsum board, gypsum backing board and gypsum base for veneer plaster as described in
(a) CAN/CSA-A82.27-M, "Gypsum Board", or
(b) ASTM C1396 / C1396M, "Standard Specification for Gypsum Board".
(2) Where the term “Type X gypsum board” is used in this Supplementary Standard, it applies to special fire-resistant
gypsum board as described in
(a) CAN/CSA-A82.27-M, "Gypsum Board", or
(b) ASTM C1396 / C1396M, "Standard Specification for Gypsum Board".
1.6.1.Method of Calculating
(1) The thickness of solid-unit masonry and concrete described in this Supplementary Standard shall be the thickness of
solid material in the unit or component thickness. For units that contain cores or voids, the Tables refer to the equivalent
thickness determined in conformance with Sentences (2) to (10).
(2) Where a plaster finish is used, the equivalent thickness of a wall, floor, column or beam protection shall be equal to
the sum of the equivalent thicknesses of the concrete or masonry units and the plaster finish measured at the point that
will give the least value of equivalent thickness.
(3) Except as provided in Sentence (5), the equivalent thickness of a hollow masonry unit shall be calculated as equal to
the actual overall thickness of a unit in millimetres multiplied by a factor equal to the net volume of the unit and divided
by its gross volume.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
(4) Net volume shall be determined using a volume displacement method that is not influenced by the porous nature of
the units.
(5) Gross volume of a masonry unit shall be equal to the actual length of the unit multiplied by the actual height of the
unit multiplied by the actual thickness of the unit.
(6) Where all the core spaces in a wall of hollow concrete masonry or hollow-core precast concrete units are filled with
grout, mortar, or loose fill materials such as expanded slag, burned clay or shale (rotary kiln process), vermiculite or
perlite, the equivalent thickness rating of the wall shall be considered to be the same as that of a wall of solid units, or a
solid wall of the same concrete type and the same overall thickness.
(7) The equivalent thickness of hollow-core concrete slabs and panels having a uniform thickness and cores of constant
cross section throughout their length shall be obtained by dividing the net cross-sectional area of the slab or panel by its
width.
(8) The equivalent thickness of concrete panels with tapered cross sections shall be the cross section determined at a
distance of 2 t or 150 mm, whichever is less, from the point of minimum thickness, where t is the minimum thickness.
(9) Except as permitted in Sentence (10), the equivalent thickness of concrete panels with ribbed or undulating surfaces
shall be
(a) ta for s less than or equal to 2 t,
(b) t + (4 t/s − 1)(ta − t) for s less than 4 t and greater than 2 t, and
(c) t for s greater than or equal to 4 t
where
t = minimum thickness of panel,
ta = average thickness of panel (unit cross-sectional area divided by unit width), and
s = centre to centre spacing of ribs or undulations.
(10) Where the total thickness of a panel described in Sentence (9), exceeds 2 t, only that portion of the panel which is
less than 2 t from the non-ribbed surface shall be considered for the purpose of the calculations in Sentence (9).
1.7.Contribution of Plaster or Gypsum Board Finish
to Fire Resistance of Masonry or Concrete
1.7.1.Determination of Contribution
(1) Except as provided in Sentences (2) to (5), the contribution of a plaster or gypsum board finish to the fire resistance
of a masonry or concrete wall, floor or roof assembly shall be determined by multiplying the actual thickness of the finish
by the factor shown in Table 1.7.1., depending on the type of masonry or concrete to which it is applied. This corrected
thickness shall then be included in the equivalent thickness as described in Subsection 1.6.
(2) Where a plaster or gypsum board finish is applied to a concrete or masonry wall, the calculated fire-resistance rating
of the assembly shall not exceed twice the fire-resistance rating provided by the masonry or concrete because structural
collapse may occur before the limiting temperature is reached on the surface of the non-fire-exposed side of the assembly.
(3) Where a plaster or gypsum board finish is applied only on the non-fire-exposed side of a hollow clay tile wall, no
increase in fire resistance is permitted because structural collapse may occur before the limiting temperature is reached on
the surface of the non-fire-exposed side of the assembly.
(4) The contribution to fire resistance of a plaster or gypsum board finish applied to the non-fire-exposed side of a
monolithic concrete or unit masonry wall shall be determined in conformance with Sentence (1), but shall not exceed
0.5 times the contribution of the concrete or masonry wall.
Page 6 • SB-2
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2024MMAH Supplementary Standard SB-2
(5) When applied to the fire-exposed side, the contribution of a gypsum lath and plaster or gypsum board finish to the
fire resistance of masonry or concrete wall, floor or roof assemblies shall be determined from Table 2.3.4.A. to 2.3.4.D.
Table 1.7.1.
Multiplying Factors for Masonry or Concrete Construction
Type of Masonry or Concrete
Type of Surface Cored Clay Brick, Clay Concrete Unit Masonry,
Solid Clay Brick, Unit
Protection Tile, Monolithic Concrete, Type L1 or L2 20S and Concrete Unit Masonry,
Masonry and Monolithic
Type L40S and Unit Monolithic Concrete, Type L2
Concrete, Type N or S
Masonry, Type L120S Type L
Portland cement-sand
plaster or lime sand 1.00 0.75 0.75 0.50
plaster
Gypsum-sand plaster,
wood fibred gypsum 1.25 1.00 1.00 1.00
plaster or gypsum board
Vermiculite or perlite
1.75 1.50 1.25 1.25
aggregate plaster
Column 1 2 3 4 5
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
1.7.2.Plaster
(1) Gypsum plastering shall conform to CSA A82.30-M, "Interior Furring, Lathing and Gypsum Plastering".
(2) Portland cement-sand plaster shall be applied in 2 coats: the first coat containing 1 part Portland cement to 2 parts
sand by volume, and the second coat containing 1 part Portland cement to 3 parts sand by volume.
(3) Plaster finish shall be securely bonded to the wall or ceiling.
(4) The thickness of plaster finish applied directly to monolithic concrete without metal lath shall not exceed 10 mm on
ceilings and 16 mm on walls.
(5) Where the thickness of plaster finish on masonry or concrete exceeds 38 mm, wire mesh with 1.57 mm diam wire
and openings not exceeding 50 mm by 50 mm shall be embedded midway in the plaster.
1.7.3.Attachment of Gypsum Board and Lath
(1) Gypsum board and gypsum lath finishes applied to masonry or concrete walls shall be secured to wood or steel
furring members in conformance with Article 2.3.9.
1.7.4.Sample Calculations
(1) The following examples are included as a guide to the method of calculating the fire resistance of concrete or hollow
masonry walls with plaster or gypsum board protection:
2024MMAH Supplementary Standard SB-2
Example (1)
A 3 h fire-resistance rating is required for a monolithic concrete wall of Type S aggregate with a 20 mm gypsum-sand
plaster finish on metal lath on each face.
(a) The minimum equivalent thickness of Type S monolithic concrete needed to give a 3 h fire-resistance rating =
158 mm (Table 2.1.1.).
(b) Since the gypsum-sand plaster finish is applied on metal lath, Sentence 1.7.1.(5) does not apply. Therefore, the
contribution to the equivalent thickness of the wall of 20 mm gypsum-sand plaster on each face of the concrete is
20 × 1.25 = 25 mm (see Sentences 1.7.1.(1) to (4)).
(c) The total contribution of the plaster finishes is 2 × 25 = 50 mm.
(d) The minimum equivalent thickness of concrete required is 158 mm - 50 mm = 108 mm.
(e) From Table 2.1.1., the 108 mm equivalent thickness of monolithic concrete gives a contribution of less than 1.5 h.
This is less than half the rating of the assembly so that the conditions in Sentence 1.7.1.(2) are not met. Thus the
equivalent thickness of monolithic concrete must be increased to 112 mm to give 1.5 h contribution.
(f) The total equivalent thickness of the plaster finishes can then be reduced to 158 mm − 112 mm = 46 mm.
(g) The total actual thickness of the plaster finishes required is therefore 46 mm ÷ 1.25 = 37 mm (Sentences 1.7.1.(1)
to (4)) or 18.5 mm on each face.
(h) Since the thickness of the plaster finish on each face exceeds 16 mm, metal lath is still required (Sentence 1.7.2.(4)).
(i) Since this wall is symmetrical with plaster on both faces, the contribution to fire resistance of the plaster finish on
either face is limited to one-quarter of the wall rating by virtue of Sentence 1.7.1.(2). Under these circumstances,
the conditions in Sentence 1.7.1.(4) are automatically met.
Example (2)
A 2 h fire-resistance rating is required for a hollow masonry wall of Type N concrete with a 12.7 mm Type X gypsum
board finish on each face.
(a) Since gypsum board is used, Sentence 1.7.1.(5) applies. The 12.7 mm gypsum board finish on the fire-exposed side
is, therefore, assigned 25 min by using Table 2.3.4.A.
(b) The fire resistance required of the balance of the assembly is 120 min − 25 min = 95 min.
(c) Interpolating between 1.5 h and 2 h in Table 2.1.1. for 95 min fire resistance, the equivalent thickness for hollow
masonry units required is 95 mm + (18 mm × 5/30) = 95 mm + 3 mm = 98 mm.
(d) The contribution to the equivalent thickness of the wall of the 12.7 mm gypsum board finish on the non-fire-exposed
side using Table 1.7.1. = 12.7 × 1.25 = 16 mm.
(e) Equivalent thickness required of concrete masonry unit = 98 − 16 = 82 mm.
(f) The fire-resistance rating of a concrete masonry wall having an equivalent thickness of 82 mm = 1 h for 73 mm +
(9 mm × 30/22) = 1 h 12 min. As this is more than 1 h, the conditions of Sentence 1.7.1.(2) are met and the rating of
2 h is justified.
Example (3)
A 2 h fire-resistance rating is required for a hollow masonry exterior wall of Type L 220S concrete with a 15.9 mm Type X
gypsum board finish on the non-fire-exposed side only.
(a) According to Table 2.1.1., the minimum equivalent thickness for Type L220S concrete masonry units needed to
achieve a 2 h rating is 94 mm.
(b) Since gypsum board is not used on the fire-exposed side, Sentence 1.7.1.(5) does not apply. The contribution to the
equivalent thickness of the wall by the 15.9 mm Type X gypsum board finish applied on the
non-fire-exposed side is 15.9 × 1 ≈ 16 mm (see Sentence 1.7.1.(1) and Table 1.7.1.).
(c) Therefore, the equivalent thickness required of the concrete masonry unit is 94 − 16 = 78 mm.
(d) The contribution to fire resistance of a 78 mm L 220S concrete hollow masonry unit is 85 min. The contribution of
the Type X gypsum board finish is 120 − 85 = 35 min, which does not exceed half the 85 min contribution of the
masonry unit or 42.5 min, so that the conditions in Sentence 1.7.1.(4) are met.
(e) The rating of the wall (120 min) is less than twice the contribution of the masonry unit (170 min) so that the
conditions in Sentence 1.7.1.(2) are also met.
Page 8 • SB-2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
1.8.1.Exposure to Fire
(1) All tests relate to the performance of a floor assembly or floor-ceiling or roof-ceiling assembly above a fire. It has
been assumed on the basis of experience that fire on top will take a longer time to penetrate the floor than one below, and
that the fire resistance in such a situation will be at least equal to that obtained from below in the standard test.
1.9.1.Effect of Moisture
(1) The moisture content of building materials at the time of fire test may have a significant influence on the measured
fire resistance. In general, an increase in the moisture content should result in an increase in the fire resistance, though in
some materials the presence of moisture may produce disruptive effects and early collapse of the assembly.
(2) Moisture content is now controlled in standard fire test methods and is generally recorded in the test reports. In
earlier tests, moisture content was not always properly determined.
1.10.1.Test Conditions
(1) The ratings in this Supplementary Standard relate to tested assemblies and do not take into account possible changes
or deterioration in use of the materials. The standard fire test measures the fire resistance of a sample building assembly
erected for the test. No judgment as to the permanence or durability of the assembly is made in the test.
1.11.1.Thermal Protection
(1) Since the ability of a steel structural member to sustain the loading for which it was designed may be impaired
because of elevated temperatures, measures shall be taken to provide thermal protection. The fire-resistance ratings, as
established by the provisions of this Supplementary Standard, indicate the time periods during which the effects of heat
on protected steel structural members are considered to be within acceptable limits.
1.12.1.Effect on Fire-Resistance Ratings
(1) In fire tests of floors, roofs and beams, it is necessary to state whether the rating applies to a thermally restrained or
thermally unrestrained assembly. Edge restraint of a floor or roof, structural continuity, or end restraint of a beam can
significantly extend the time before collapse in a standard test. A restrained condition is one in which expansion or
rotation at the supports of a load-carrying element resulting from the effects of fire is resisted by forces or moments
external to the element. An unrestrained condition is one in which the load-carrying element is free to thermally expand
and rotate at its supports.
2024MMAH Supplementary Standard SB-2
Whether an assembly or structural member can be considered thermally restrained or thermally unrestrained depends on
the type of construction and location in a building. Guidance on this subject can be found in Appendix A of
CAN/ULC-S101, "Standard Method of Fire Endurance Tests of Building Construction and Materials". Different
acceptance criteria also apply to thermally unrestrained and thermally restrained assemblies. These are described in
CAN/ULC-S101.
The ratings for floors, roofs, and beams in this Supplementary Standard meet the conditions of CAN/ULC-S101,
"Standard Method of Fire Endurance Tests of Building Construction and Materials" for thermally unrestrained specimens.
In a thermally restrained condition, the structural element or assembly would probably have greater fire resistance, but the
extent of this increase can be determined only by reference to behavior in a standard test.
Section 2 Fire-Resistance Ratings
2.1.1.Minimum Equivalent Thickness for Fire-Resistance Rating
(1) The minimum thicknesses of unit masonry and monolithic concrete walls are shown in Table 2.1.1. Hollow
masonry units and hollow-core concrete panels shall be rated on the basis of equivalent thickness as described in
Subsection 1.6.
Table 2.1.1.
Minimum Equivalent Thicknesses(1) of Unit Masonry and Monolithic Concrete Walls Loadbearing and Non-Loadbearing, mm
Fire-Resistance Rating
Type of Wall
30 min 45 min 1h 1.5 h 2h 3h 4h
Solid brick units (80% solid and over), actual overall thickness 63 76 90 108 128 152 178
Cored brick units and hollow tile units (less than 80% solid),
50 60 72 86 102 122 142
equivalent thickness
Solid and hollow concrete masonry units, equivalent thickness
Type S or N concrete(2) 44 59 73 95 113 142 167
Type L120S concrete 42 54 66 87 102 129 152
Type L1 concrete 42 54 64 82 97 122 143
Type L220S concrete 42 54 64 81 94 116 134
Type L2 concrete 42 54 63 79 91 111 127
Monolithic concrete and concrete panels, equivalent thickness
Type S concrete 60 77 90 112 130 158 180
Type N concrete 59 74 87 108 124 150 171
Type L40S or Type L concrete 49 62 72 89 103 124 140
Column 1 2 3 4 5 6 7 8
Notes to Table 2.1.1.:
(1) See definition of equivalent thickness in Subsection 1.6.
(2) Hollow concrete masonry units made with Type S or N concrete shall have a minimum compressive strength of 15 MPa based on net
area, as defined in CSA A165.1, "Concrete block masonry units".
Page 10 • SB-2
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2.1.2.Applicability of Ratings
(1) Ratings obtained as described in Article 2.1.1. apply to either loadbearing or non-loadbearing walls, except for walls
described in Sentences (2) to (6).
(2) Ratings for walls with a thickness less than the minimum thickness prescribed for loadbearing walls in this
Supplementary Standard apply to non-loadbearing walls only.
(3) Masonry cavity walls (consisting of 2 wythes of masonry with an air space between) that are loaded to a maximum
allowable compressive stress of 380 kPa have a fire resistance at least as great as that of a solid wall of a thickness equal
to the sum of the equivalent thicknesses of the 2 wythes.
(4) Masonry cavity walls that are loaded to a compressive stress exceeding 380 kPa are not considered to be within the
scope of this Supplementary Standard.
(5) A masonry wall consisting of 2 types of masonry units, either bonded together or in the form of a cavity wall, shall
be considered to have a fire-resistance rating equal to that which would apply if the whole of the wall were of the material
that gives the lesser rating.
(6) A non-loadbearing cavity wall made up of 2 precast concrete panels with an air space or insulation in the cavity
between them shall be considered to have a fire-resistance rating as great as that of a solid wall of a thickness equal to the
sum of the thicknesses of the 2 panels.
2.1.3.Framed Beams and Joists
(1) Beams and joists that are framed into a masonry or concrete fire separation shall not reduce the thickness of the fire
separation to less than the equivalent thickness required for the fire separation.
2.1.4.Credit for Plaster Thickness
(1) On monolithic walls and walls of unit masonry, the full plaster finish on one or both faces multiplied by the factor
shown in Table 1.7.1. shall be included in the wall thickness shown in Table 2.1.1., under the conditions and using the
methods described in Subsection 1.7.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.1.5.Walls Exposed to Fire on Both Sides
(1) Except as permitted in Sentence (2), portions of loadbearing reinforced concrete walls, which do not form a
complete fire separation and thus may be exposed to fire on both sides simultaneously, shall have minimum dimensions
and minimum cover to steel reinforcement in conformance with Articles 2.8.2. to 2.8.5.
(2) A concrete wall exposed to fire from both sides as described in Sentence (1) has a fire-resistance rating of 2 h if the
following conditions are met:
(a) its equivalent thickness is not less than 200 mm,
(b) its aspect ratio (width/thickness) is not less than 4.0,
(c) the minimum thickness of concrete cover over the steel reinforcement specified in Clause (d) is not less than 50 mm,
(d) each face of the wall is reinforced with both vertical and horizontal steel reinforcement in conformance with either
Clause 10 or Clause 14 of CSA A23.3, "Design of concrete structures",
(e) the structural design of the wall is governed by the minimum eccentricity (15 + 0.03h) specified in Clause 10.15.3.1.
of CSA A23.3, "Design of concrete structures", and
(f) the effective length of the wall, klu, is not more than 3.7 m
where
k = effective length factor obtained from CSA A23.3, "Design of concrete structures",
lu = unsupported length of the wall in metres.
2.2.1.Assignment of Rating
(1) Floors and roofs in a fire test are assigned a fire-resistance rating which relates to the time that an average
temperature rise of 140°C or a maximum temperature rise of 180°C at any location is recorded on the unexposed side, or
the time required for collapse to occur, whichever is the lesser. The thickness of concrete shown in Table 2.2.1.A. shall
be required to resist the transfer of heat during the fire resistance period shown.
(2) The concrete cover over the reinforcement and steel tendons shown in Table 2.2.1.B. shall be required to maintain
the integrity of the structure and prevent collapse during the same period.
Table 2.2.1.A.
Minimum Thickness of Reinforced and Prestressed Concrete Floor or Roof Slabs, mm
Fire-Resistance Rating
Type of Concrete
30 min 45 min 1h 1.5 h 2h 3h 4h
Type S concrete 60 77 90 112 130 158 180
Type N concrete 59 74 87 108 124 150 171
Type L40S or Type L concrete 49 62 72 89 103 124 140
Column 1 2 3 4 5 6 7 8
Table 2.2.1.B.
Minimum Concrete Cover Over Reinforcement in Concrete Slabs, mm
Fire-Resistance Rating
Type of Concrete
30 min 45 min 1h 1.5 h 2h 3h 4h
Type S, N, L40S or L concrete 20 20 20 20 25 32 39
Prestressed concrete slabs Type S, N, L40S or L
20 25 25 32 39 50 64
Concrete
Column 1 2 3 4 5 6 7 8
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.2.2.Floors With Hollow Units
(1) The fire resistance of floors containing hollow units may be determined on the basis of equivalent thickness as
described in Subsection 1.6.
2.2.3.Composite Slabs
(1) For composite concrete floor and roof slabs consisting of one layer of Type S or N concrete and another layer of
Type L40S or L concrete in which the minimum thickness of both the top and bottom layers is not less than 25 mm, the
combined fire-resistance rating may be determined using the following expressions:
(a) when the base layer consists of Type S or N concrete,
8.7
R = 0.00018 t 2 − 0.00009 dt +
t
Page 12 • SB-2
2024MMAH Supplementary Standard SB-2
(b) when the base layer consists of Type L40S or L concrete,
6.4
R = 0.0001 t 2 + 0.0002 dt − 0.0001d 2 +
t
where
R = fire resistance of slab, h,
t = total thickness of slab, mm, and
d = thickness of base layer, mm.
(2) If the base course described in Sentence (1) is covered by a top layer of material other than Type S, N, L40S or L
concrete, the top course thickness may be converted to an equivalent concrete thickness by multiplying the actual
thickness by the appropriate factor listed in Table 2.2.3.A. This equivalent concrete thickness may be added to the
thickness of the base course and the fire-resistance rating calculated using Table 2.2.1.A.
(3) The minimum concrete cover under the main reinforcement for composite concrete floor and roof slabs with base
slabs less than 100 mm thick shall conform to Table 2.2.3.B. For base slabs 100 mm or more thick, the minimum cover
thickness requirements of Table 2.2.1.B. shall apply.
(4) Where the top layer of a 2-layer slab is less than 25 mm thick, the fire-resistance rating for the slab shall be
calculated as though the entire slab were made up of the type of concrete with the lesser fire resistance.
Table 2.2.3.A.
Multiplying Factors for Equivalent Thickness
Base Slab Normal Density Base Slab Low Density
Top Course Material
Concrete (Type S or N) Concrete (Type L40S or L)
Gypsum board 3.00 2.25
Cellular concrete (mass density 400 - 560 kg/m3) 2.00 1.50
Vermiculite and perlite concrete (mass density 560 kg/m3 or less) 1.75 1.50
Portland cement with sand aggregate 1.00 0.75
Terrazzo 1.00 0.75
Column 1 2 3
Table 2.2.3.B.
Minimum Concrete Cover Under Bottom Reinforcement in Composite Concrete Slabs, mm
Fire-Resistance Rating
Base Slab Concrete Type
30 min 45 min 1h 1.5 h 2h 3h 4h
Reinforced concrete
Type S, N, L40S or L 15 15 20 25 30 40 55
Prestressed concrete
Type S 20 25 30 40 50 65 75
Type N 20 20 25 35 45 60 70
Type L40S or L 20 20 25 30 40 50 60
Column 1 2 3 4 5 6 7 8
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.2.4.Contribution of Plaster Finish
(1) The contribution of plaster finish securely fastened to the underside of concrete may be taken into account in floor or
roof slabs under the conditions and using the methods described in Subsection 1.7.
(2) Plaster finish on the underside of concrete floors or roofs may be used in lieu of concrete cover referred to in
Sentence 2.2.1.(2) under the conditions and using the methods described in Subsection 1.7.
2.2.5.Concrete Cover
(1) In prestressed concrete slab construction, the concrete cover over an individual tendon shall be the minimum
thickness of concrete between the surface of the tendon and the fire-exposed surface of the slab, except that for ungrouted
ducts the assumed cover thickness shall be the minimum thickness of concrete between the surface of the duct and the
bottom of the slab. For slabs in which several tendons are used, the cover is assumed to be the average of those of
individual tendons, except that the cover for any individual tendon shall be not less than half of the value given in
Table 2.2.1.B. nor less than 20 mm.
(2) Except as provided in Sentence (3), in post-tensioned prestressed concrete slabs, the concrete cover to the tendon at
the anchor shall be not less than 15 mm greater than the minimum cover required by Sentence (1). The minimum
concrete cover to the anchorage bearing plate and to the end of the tendon, if it projects beyond the bearing plate, shall be
20 mm.
(3) The requirements of Sentence (2) do not apply to those portions of slabs not likely to be exposed to fire, such as the
ends and tops.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.2.6.Minimum Dimensions for Cover
(1) Minimum dimensions and cover to steel tendons of prestressed concrete beams shall conform to Subsection 2.10.
2.3. Wood and Steel Framed Walls, Floors and Roofs
2.3.1.Maximum Fire-Resistance Rating
(1) The fire-resistance rating of walls constructed of wood studs or cold-formed-steel studs, of floors constructed of
wood joists, wood I-joists, pre-manufactured wood trusses, cold-formed-steel joists or open web steel joists, and of roofs
constructed of wood joists, pre-manufactured metal-plate-connected wood trusses or open web steel joists, can be
determined for ratings of not more than 90 min from the information in this Subsection.
2.3.2.Loadbearing Conditions
(1) The fire-resistance ratings derived from the information in this Subsection apply to loadbearing and non-loadbearing
wood-framed and cold-formed-steel-framed walls, and to loadbearing floors and roofs, as specifically described in this
Subsection.
(2) Loadbearing conditions shall be as defined in CAN/ULC-S101, "Standard Method of Fire Endurance Tests of
Building Construction and Materials".
Page 14 • SB-2
2.3.3.Limitations of Component Additive Method
(See Section 7 Background Information.)
(1) The fire-resistance rating of a framed assembly depends primarily on the time during which the membrane on the
fire-exposed side remains in place.
(2) The assigned times in Sentences 2.3.4.(2) to (4) are not intended to be construed as the fire-resistance ratings of the
individual components of an assembly, nor are they intended to be construed as times that are applicable or acceptable for
use beyond the method and systems described in this Subsection. These assigned times are the individual contributions of
each component to the overall fire-resistance rating of an assembly, which are permitted to be derived using the
component additive method described in this Subsection..
(3) The fire-resistance rating calculated by the component additive method cannot be increased by installing membranes
in multiple layers, other than as specified in Tables 2.3.4.A., 2.3.4.B. and 2.3.4.C.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.4.Method of Calculation
(1) In the component additive method, the fire-resistance rating of a framed assembly is calculated by adding the time
assigned in Sentence (2) for the membrane on the fire-exposed side to the time assigned in Sentence (3) for the framing
members and then adding any time assigned in Sentence (4) for additional protective measures, such as the inclusion of
insulation or of reinforcement of a membrane. For loadbearing walls where resilient metal channels are installed with a
single layer of gypsum board membrane in accordance with Table 2.3.4.A, the fire-resistance rating determined using this
method of calculation must be reduced by 10 min.
(2) The times to be used in the component additive method that have been assigned to membranes on the fire-exposed
side of the assembly, which are partly based on their ability to remain in place during fire tests, are listed in
Tables 2.3.4.A., 2.3.4.B., 2.3.4.C. and 2.3.4.D. (This is not to be confused with the fire-resistance rating of the
membrane, which also takes into account the rise in temperature on the unexposed side of the membrane. [See Sentence
2.3.3.(2).])
(3) The times to be used in the component additive method that have been assigned to wall framing members and to
floor and roof framing members are listed in Tables 2.3.4.E. and 2.3.4.F. respectively.
(4) Preformed insulation of glass, rock or slag fibre and cellulose fibre insulation provide additional protection to wood
studs by shielding the studs from exposure to the fire and thus delaying the time of collapse. The use of preformed glass
fibre, preformed rock or slag fibre and dry-blown cellulose insulation material does not decrease the rating of wall
assemblies with the membranes identified in Table 2.3.4.A. Similarly, the use of preformed glass fibre, preformed rock
or slag fibre and cellulose insulation material does not decrease the rating of floors joists constructed with wood joists,
wood trusses, wood I-joists and cold-formed-steel floor joists (C-shaped joists), provided the insulation is not in direct
contact with the members identified in Table 2.3.4.B. The use of reinforcement in the membrane exposed to fire also
adds to the fire resistance by extending the time to failure. Table 2.3.4.G. shows the time increments that may be added to
the fire resistance if these features are incorporated in the assembly.
(5) Cellulose fibre insulation conforming to CAN/ULC-S703, "Standard for Cellulose Fibre Insulation for Buildings",
applied in conformance with CAN/CGSB-92.2-M, "Trowel or Spray Applied Acoustical Material", does not affect the
fire-resistance rating of a non-loadbearing cold-formed-steel stud wall assembly, provided that it is sprayed to either face
of the wall cavity.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.3.4.A.
Time Assigned to Protective Membranes on Fire-Exposed Side of Wood-Framed and Cold-Formed-Steel-Framed Walls
Time, min
Description of Finish
Loadbearing Walls Non-Loadbearing Walls
11.0 mm Douglas Fir plywood phenolic bonded — 10(1)
14.0 mm Douglas Fir plywood phenolic bonded — 15(1)
12.7 mm Type X gypsum board 25(2) 25
15.9 mm Type X gypsum board 40(2) 40(3)
Double 12.7 mm Type X gypsum board(4) 50 80
Column 1 2 3
Notes to Table 2.3.4.A.:
(1) Applies to stud cavities filled with mineral wool conforming to CAN/ULC-S702.1, "Standard for Mineral Fibre Thermal Insulation for
Buildings, Part 1: Material Specification", and having a mass per unit area of not less than 2 kg/m2, with no additional credit for
insulation according to Table 2.3.4.G.
(2) Applies only to wood-framed walls.
(3) Applies only to steel-framed walls.
(4) Resilient metal channels are permitted to be installed at a spacing of 406 mm o.c. with no effect on the rating of the wall assembly.
Table 2.3.4.B.
Time Assigned to Gypsum Board Membranes on Fire-Exposed Side of Floors
Time, min
Description of Finish Resilient Metal Channels(1)
Floors with Wood or Steel Joists Floors with Open-Web Steel Joists
12.7 mm Type X gypsum board 25(3) −
Spaced ≤ 406 mm o.c.(2)
15.9 mm Type X gypsum board 40 −
12.7 mm Type X gypsum board 25(4) 25
—
15.9 mm Type X gypsum board 40(4) 40
Double 12.7 mm Type X gypsum board Spaced ≤ 406 mm o.c.(5) 50(3) —
Double 12.7 mm Type X gypsum board Spaced at 610 mm o.c.(6) 45(3) —
Double 15.9 mm Type X gypsum board Spaced ≤ 610 mm o.c.(6) 60(3) —
Column 1 2 3 4
Notes to Table 2.3.4.B.:
(1) See Figures 1, 2 and 4 in MMAH Supplementary Standard SB-3, “Fire and Sound Resistance Tables” for the attachment of single and
double layers of gypsum board to resilient metal channels.
(2) Resilient metal channels must be installed to achieve the stated rating.
(3) Applies to wood joists, wood trusses, wood I-joists and cold-formed steel joists (C-shaped joists).
(4) Applies to wood joists and pre-fabricated metal-plate-connected wood trusses.
(5) Resilient metal channels must be installed or gypsum board must be applied directly to the structural members, which must be spaced
not more than 406 mm o.c.
(6) Resilient metal channels are permitted to be installed with no effect on the rating of the floor assembly. Gypsum board is also
permitted to be applied directly to the structural members.
Page 16 • SB-2
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2024MMAH Supplementary Standard SB-2
Table 2.3.4.C.
Time Assigned to Gypsum Board Membranes on Fire-Exposed Side of Roofs
Description of Finish Time, min(1)
12.7 mm Type X gypsum board 25
15.9 mm Type X gypsum board 40
Column 1 2
Notes to Table 2.3.4.C.:
(1) Applies to wood joists, pre-fabricated metal-plate-connected wood trusses and open-web steel joists with ceiling supports spaced not
more than 406 mm o.c.
Table 2.3.4.D.
Time Assigned for Contribution of Lath and Plaster Protection on Fire-Exposed Side
Type of Plaster Finish
Portland Cement and Gypsum and Sand or Gypsum and Perlite or
Type of Lath Plaster Thickness, mm
Sand(1) or Lime and Sand Gypsum Wood Fibre Gypsum and Vermiculite
Time, min(2)
13 — 35 55
9.5 mm gypsum 16 — 40 65
19 — 50 80(3)
19 20 50 80(3)
Metal 23 25 65 80(3)
26 30 80 80(3)
Column 1 2 3 4 5
Notes to Table 2.3.4.D.:
(1) For mixture of Portland cement-sand plaster, see Sentence 1.7.2.(2).
(2) Applies to loadbearing and non-loadbearing wood studs or non-loadbearing cold-formed-steel studs, to floors constructed of wood
joists or open-web steel joists, and to roofs constructed of wood joists, pre-manufactured metal-plate-connected wood trusses or open-
web steel joists.
(3) Values shown for these membranes have been limited to 80 min because the fire-resistance ratings of framed assemblies derived
from these Tables must not exceed 1.5 h.
Table 2.3.4.E.
Time Assigned for Contribution of Wood-Framed or Cold-Formed-Steel-Framed Walls
Time, min
Description of Frame
Loadbearing Walls Non-Loadbearing Walls
Wood studs spaced ≤ 406 mm o.c. 20 20
Wood studs spaced ≤ 610 mm o.c. 15 15
Cold-formed-steel studs spaced ≤ 406 mm o.c. 10 10
Cold-formed-steel studs spaced ≤ 610 mm o.c. 10 —
Column 1 2 3
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.3.4.F.
Time Assigned for Contribution of Wood or Steel Frame of Floors and Roofs
Description of Frame
Time, min
Type of Assembly Structural Members
Wood joists, wood I-joists, wood trusses and cold-formed-steel joists spaced ≤ 610 mm o.c.
Floor(1) 10(2)
Open-web steel joists with ceiling supports spaced ≤ 406 mm o.c.
Wood joists spaced ≤ 406 mm o.c. 10
Roof Open-web steel joists with ceiling supports spaced ≤ 406 mm o.c. 10
Wood truss assemblies (metal-plate-connected) spaced ≤ 610 mm o.c. 5
Column 1 2 3
Notes to Table 2.3.4.F.:
(1) Resilient metal channels are permitted to be installed with no effect on the rating of the floor assembly.
(2) Applies only to floor structural members that are protected by a membrane.
Table 2.3.4.G.
Time Assigned for Additional Protection
Description of Additional Protection Time, min
Add to the fire-resistance rating of wood stud walls, sheathed with gypsum board or lath and plaster, if the spaces
between the studs are filled with preformed insulation of rock or slag fibres conforming to CAN/ULC-S702.1, "Standard
15(1)
for Mineral Fibre Thermal Insulation for Buildings, Part 1: Material Specification", and with a mass per unit area of not
less than 1.22 kg/m2 of wall surface
Add to the fire-resistance rating of non-loadbearing wood stud walls, sheathed with gypsum board or lath and plaster, if
the spaces between the studs are filled with preformed insulation of glass fibres conforming to CAN/ULC- S702.1,
5(2)
"Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1: Material Specification", and having a mass per unit
area of not less than 0.6 kg/m2 of wall surface
Add to the fire-resistance rating of loadbearing wood stud walls, sheathed with gypsum board if the spaces between the
studs are filled with of cellulose fibres conforming to CAN/ULC-S703, "Standard for Cellulose Fibre Insulation for 10
Buildings", and having a density of not less than 50 kg/m3
Add to the fire-resistance rating of plaster on gypsum lath ceilings if 0.76 mm diam wire mesh with 25 mm by 25 mm
openings or 1.57 mm diam diagonal wire reinforcing at 250 mm o.c. is placed between lath and plaster
Add to the fire-resistance rating of plaster on gypsum lath ceilings if 76 mm wide metal lath strips are placed over joints
between lath and plaster
Add to the fire-resistance rating of plaster on 9.5 mm thick gypsum lath ceilings (Table 2.3.4.D.) if supports for lath are
305 mm o.c.
Add to the fire-resistance rating of floor assemblies if the spaces between the structural member are filled with
preformed insulation of rock or slag fibres conforming to CAN/ULC-S702.1, "Standard for Mineral Fibre Thermal
5(2)
Insulation for Buildings, Part 1: Material Specification", and having a mass per unit area of not less than 1.22 kg/m2 of
floor surface
Add to the fire-resistance rating of floor assemblies if the spaces between the structural members studs are filled with
wet-blown cellulose fibres conforming to CAN/ULC-S703, "Standard for Cellulose Fibre Insulation for Buildings", and 5(2)(3)
having a density of not less than 50 kg/m3
Add to the fire-resistance rating of floor assemblies where the floor topping on the unexposed side of the floor
5(2)
assemblies consists of concrete not less than 38 mm thick
Column 1 2
Page 18 • SB-2
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2024MMAH Supplementary Standard SB-2
Notes to Table 2.3.4.G.:
(1) Applies to wood-framed walls only.
(2) Applies to wood joists, wood trusses, wood I-joists and cold-formed-steel joists (C-shaped joists).
(3) Applies to cellulose fibre:
(i) for wood joists, wood I-joist and wood trusses − that is sprayed-applied with a minimum density of 50 kg/m3, a minimum depth
of 90 mm on the underside of the subfloor, and of 90 mm on the sides of the structural members.
(ii) for cold-formed-steel joists – that is spray-applied with a minimum density of 50 kg/m3 and a minimum thickness of 90 mm on
the underside of the subfloor, of 90 mm on the sides of the structural members, and of 13 mm on the underside of the bottom
flange other than at resilient metal channel locations.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.5.Considerations for Various Types of Assemblies
(1) Interior vertical fire separations are to be rated for exposure to fire on each side (See Sentence 3.1.3.7.(2) of
Division B of the 2024 Building Code). The method described in this Subsection applies when a membrane is provided
on both sides of the assembly. However, in the calculation of the fire-resistance rating of such an assembly using this
method, no additional contribution to fire-resistance is to be assigned for a membrane on the non-fire-exposed side, since
its contribution is already accounted for in the values assigned to the other components of the assembly.
(2) Exterior wall assemblies required to have a fire-resistance rating are required to be rated for exposure to fire from
the interior side only (See Sentence 3.1.3.7.(3) of Division B of the 2024 Building Code). When deriving a fire-
resistance rating for such wall assemblies using the method described in this Subsection, only wood studs with a single
layer of gypsum board or non-loadbearing cold-formed-steel studs conforming to Table 2.3.4.E. may be used. Such walls
must have a membrane on the exterior side of the stud consisting of plywood, oriented strandboard or gypsum sheathing
and exterior cladding. Additional materials are also permitted between the required sheathing and cladding. The spaces
between the studs are to be filled with insulation conforming to CAN/ULC-S702.1, "Standard for Mineral Fibre Thermal
Insulation for Buildings, Part 1: Material Specification", and having a mass per unit area of not less than 1.22 kg/m2 of
wall surface. However, in the calculation of the fire-resistance rating of such an assembly, no additional contribution to
fire resistance is to be assigned for a membrane on the non-fire-exposed side, since its contribution is already accounted
for in the values assigned to the other components of the assembly.
(3) In the case of a floor or roof assembly, the Building Code only requires testing for fire exposure from below. Floors
or roofs must have an upper flooring or roofing membrane in accordance with Table 2.3.5.
(4) Insulation used in the cavities of a wood joist or metal-plate-connected wood truss floor assembly with a single layer
of gypsum board will not reduce the assigned fire-resistance rating of the assembly provided:
(a) the insulation is preformed of rock, slag or glass fibre conforming to CAN/ULC-S702.1, "Standard for Mineral
Fibre Thermal Insulation for Buildings, Part 1: Material Specification", and having a mass per unit area of not more
than 1.1 kg/m2 and is installed adjacent to the bottom edge of the framing member, directly above steel furring
channels,
(b) the gypsum board ceiling membrane is attached to
(i) wood trusses in conformance with Sentence 2.3.9.(2) by way of steel furring channels spaced not more than
406 mm o.c., and the channels are secured to each bottom truss member with a double strand of 1.2 mm
galvanized steel wire, or
(ii) wood joists by way of resilient metal or steel furring channels spaced not more than 406 mm o.c. in
conformance with Sentences 2.3.9.(2) and (3), and
(c) a steel furring channel is installed midway between each furring channel mentioned in Clause (b) to provide
additional support for the insulation.
(5) Except as required in Sentence 2.3.5.(4), resilient metal or steel furring channels may be used to attach a gypsum
board ceiling membrane to a floor assembly using wood joists, metal-plate-connected wood trusses and open-web steel
joists, or to a roof assembly. The channels must be made of galvanized steel not less than 0.5 mm thick spaced not more
than 610 mm o.c. perpendicular to the framing membranes, with an overlap of not less than 100 mm at splices and a
minimum end clearance between the channels and walls of 15 mm.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.3.5.
Flooring of Roofing Membranes
Type of
Structural Members Subfloor or Roof Deck Finish Flooring or Roofing
Assembly
Hardwood or softwood flooring on building
paper
12.5 mm plywood or
Wood or open-web steel joists(1) 15.5 mm oriented strandboard or Resilient flooring, parquet floor, felted
and metal-plate-connected wood 17 mm T & G softwood, or synthetic fibre floor coverings, carpeting,
trusses(1) 14 mm phenolic-bonded Douglas Fir or ceramic tile on 8 mm thick panel-type
plywood (no finished flooring required) underlay
Floor Ceramic tile on 30 mm mortar bed
50 mm reinforced concrete or
50 mm concrete on metal lath or formed
Open-web steel joists(1) steel sheet, or Finish flooring
40 mm reinforced gypsum-fibre concrete
on 12.7 mm gypsum board
Wood joists, wood I-joists, wood
Minimum 15.5 mm T&G plywood or
trusses and cold-formed-steel No requirement
Minimum 15.5 mm oriented strandboard
joists
12.5 mm plywood or
15.5 mm oriented strandboard or
Wood or open-web steel joists(1) Finish roofing material with or without
17 mm T & G softwood, or
and wood trusses(1) insulation
14 mm phenolic-bonded Douglas Fir
plywood (no finished flooring required)
Roof
50 mm reinforced concrete or
50 mm concrete on metal lath or formed
Finish roofing material with or without
Open-web steel joists(1) steel sheet or
insulation
40 mm reinforced gypsum-fibre concrete
on 12.7 mm gypsum board
Column 1 2 3 4
Notes to Table 2.3.5.:
(1) Applies to single layer of gypsum board membrane, and lath and plaster.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.6.Framing Members
(1) The values shown in Tables 2.3.4.A., 2.3.4.B., 2.3.4.D. and 2.3.12. apply to membranes supported on framing
members installed in their conventional orientation and spaced in conformance with Tables 2.3.4.E. and 2.3.4.F.
(2) Wood studs and wood roof framing members are to be not less than 38 mm by 89 mm. Wood floor joists are to be
not less than 38 mm by 184 mm, except where they are used in an assembly from Table 2.3.4.D. or from Table 2.3.5. that
uses a single layer of gypsum board as the lower (ceiling) membrane, in which case, wood floor joists are to be not less
than 38 mm by 89 mm.
(3) Wood roof trusses are to consist of wood chord and web framing members not less than 38 mm by 89 mm and metal
connector plates fabricated from galvanized steel not less than 1 mm in nominal thickness with projecting teeth not less
than 8 mm long.
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2024MMAH Supplementary Standard SB-2
(4) Wood floor trusses are to consist of:
(a) metal-plate-connected wood trusses that are not less than 305 mm deep with wood chord and web framing members
not less than 38 mm by 64 mm and metal connector plates fabricated from galvanized steel not less than 1 mm in
nominal thickness with projecting teeth not less than 8 mm long,
(b) metal-web wood trusses that are not less than 286 mm deep with wood chords not less than 38 mm by 64 mm and
V-shaped webs made from galvanized steel not less than 1 mm in nominal thickness with plate areas having
projecting teeth not less than 8 mm long, or.
(c) fingerjoined wood trusses that are not less than 330 mm deep with fingerjoined connections, chord members not less
than 38 mm by 64 mm, and web members not less than 38 mm by 38 mm glued together with a R-14 phenol-
resorcinol resin conforming to CSA O112.10, "Evaluation of Adhesives for Structural Wood Products (Limited
Moisture Exposure)”.
(5) Wood I-joists are to be not less than 241 mm deep with flanges that are not less than 38 mm by 38 mm and an
oriented strandboard or plywood web that is not less than 9.5 mm thick.
(6) The dimensions for dressed lumber given in CSA O141, "Softwood lumber", are to be used for wood studs, joists, I-
joists and trusses.
(7) Cold-formed-steel studs for non-loadbearing walls are to consist of galvanized steel that is not less than
0.5 mm thick and not less than 63 mm wide, and have a flange width that is not less than 31 mm wide.
(8) Cold-formed-steel studs in non-loadbearing wall assemblies are to be installed with not less than a 12 mm clearance
between the top of the stud and the top of the runner to allow for expansion in the event of a fire. Where the studs are
required to be attached for alignment purposes during erection, they must be attached to the bottom runners only.
(9) Cold-formed-steel studs for loadbearing walls are to consist of galvanized steel that is not less than 0.912 mm thick
but not greater than 1.52 mm thick, with a C-shaped cross-section not less than 92 mm deep by 41 mm wide and 12.7 mm
stiffening lips.
(10) Cold-formed-steel studs in loadbearing wall assemblies are to be installed with diagonal cross-bracing.
(11) Cold-formed-steel floor joists (C-shaped joists) are to be not less than 41 mm wide by 203 mm deep by 1.22 mm
material thickness.
(12) The allowable spans for wood joists listed in the Span Tables in Part 9 of Division B of the Building Code are
provided for floors supporting specific occupancies.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.7.Plaster Finish
(1) The thickness of plaster finish shall be measured from the face of gypsum or metal lath.
2.3.8.Edge Support for Gypsum Board in Wall Assembly
(1) Gypsum board installed over framing or furring in a wall assembly shall be installed so that all edges are supported,
except that 15.9 mm Type X gypsum board may be installed horizontally with the horizontal joints unsupported when
framing members are at 406 mm o.c. maximum.
2.3.9.Membrane Fastening
(1) Except as provided in Sentences (2) to (5), Table 2.3.4.B. and Sentence 2.3.5.(5), the application of lath and plaster
finish shall conform to CSA A82.30-M, "Interior Furring, Lathing and Gypsum Plastering", and of gypsum board finish
shall conform to ASTM C840, “Standard Specification for Application and Finishing of Gypsum Board".
(2) Where a membrane referred to in Table 2.3.4.A., 2.3.4.B., 2.3.4.C., 2.3.4.D. or 2.3.12. is applied to steel framing or
furring, fasteners shall penetrate not less than 10 mm through the metal.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
(3) Except as provided in Sentence (4), where a membrane referred to in Table 2.3.4.A., 2.3.4.B., 2.3.4.C., 2.3.4.D. or
2.3.12. is applied to wood framing or furring, minimum fastener penetrations into wood members shall conform to Table
2.3.9. for the time assigned to the membrane.
(4) Where a membrane is applied in 2 layers, the fastener penetrations described in Table 2.3.9. shall apply to the base
layer. Fasteners for the face layer shall penetrate not less than 20 mm into wood supports.
(5) In a double layer application of gypsum board on wood supports, fastener spacing shall conform to ASTM C840,
“Standard Specification for Application and Finishing of Gypsum Board".
Table 2.3.9.
Membrane Fastening
Minimum Penetration of Fasteners for Membrane Protection on Wood Framing, mm
Type of 5 – 25 30 – 35 40 50 55 – 70 80
Membrane
Time,(1) min
Single layer 20 29 32 — — —
Double layer 20 20 20 29 35 44
Gypsum lath 20 20 23 23 29 29
Column 1 2 3 4 5 6 7
Notes to Table 2.3.9.:
(1) Assigned contributions of membranes to fire resistance are listed in Tables 2.3.4.A., 2.3.4.B., 2.3.4.C., 2.3.4.D. and 2.3.12.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.10.Ceiling Membrane Openings - Combustible Construction
(1) Except as permitted in Article 2.3.12., where a floor or roof assembly of combustible construction is assigned a
fire-resistance rating on the basis of this Subsection and incorporates a ceiling membrane described in Table 2.3.4.B.,
2.3.4.C. or 2.3.4.D., the ceiling membrane may be penetrated by openings leading to ducts within concealed spaces above
the membrane provided:
(a) the assembly is not required to have a fire-resistance rating in excess of 1 h,
(b) the area of any openings does not exceed 930 cm 2 (see Sentence (2)),
(c) the aggregate area of openings does not exceed 1% of the ceiling area of the fire compartment,
(d) the depth of the concealed space above the ceiling is not less than 230 mm,
(e) no dimension of any opening exceeds 310 mm,
(f) supports are provided for openings with any dimension exceeding 150 mm where framing members are spaced
greater than 406 mm o.c.,
(g) individual openings are spaced not less than 2 m apart,
(h) the ducts above the membrane are sheet steel and are supported by steel strapping firmly attached to the framing
members, and
(i) the clearance between the top surface of the membrane and the bottom surface of the ducts is not less than 100 mm.
(2) Where an individual opening permitted in Sentence (1) exceeds 130 cm 2 in area, it shall be protected by
(a) a fire stop flap conforming to CAN/ULC-S112.2, “Standard Method of Fire Test of Ceiling Firestop Flap
Assemblies”, that activates at a temperature approximately 30°C above the normal maximum temperature that
occurs in the ducts, whether the air duct system is operating or shut down, or
(b) thermal protection above the duct consisting of the same materials as used for the ceiling membrane, mechanically
fastened to the ductwork and extending 200 mm beyond the opening on all sides (see Figure 2.3.10.).
Page 22 • SB-2
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2024MMAH Supplementary Standard SB-2
Figure 2.3.10.
Thermal Protection Above a Duct
2.3.11.Ceiling Membrane Openings - Noncombustible Construction
(1) Except as permitted in Article 2.3.12., where a floor or roof assembly of noncombustible construction is assigned a
fire-resistance rating on the basis of this Subsection and incorporates a ceiling membrane described in Table 2.3.4.B.,
2.3.4.C. or 2.3.4.D. the ceiling membrane may be penetrated by openings leading to ducts located within concealed spaces
provided:
(a) the area of any opening does not exceed 930 cm 2 (see Sentence (2)),
(b) the aggregate area of openings does not exceed 2% of the ceiling area of the fire compartment,
(c) no dimension of any opening exceeds 400 mm,
(d) individual openings are spaced not less than 2 m apart,
(e) openings are located not less than 200 mm from major structural members such as beams, columns or joists,
(f) the ducts above the membrane are sheet steel and are supported by steel strapping firmly attached to the framing
members, and
(g) the clearance between the top surface of the membrane and the bottom surface of the duct is not less than 100 mm.
(2) Where an individual opening permitted in Sentence (1) exceeds 130 cm 2 in area, it shall be protected by
(a) a fire stop flap conforming to CAN/ULC-S112.2, “Standard Method of Fire Test of Ceiling Firestop Flap
Assemblies”, that activates at a temperature approximately 30°C above the normal maximum temperature that
occurs in the ducts, whether the air duct system is operating or shut down, or
(b) thermal protection above the duct consisting of the same materials as used for the ceiling membrane, mechanically
fastened to the ductwork and extending 200 mm beyond the opening on all sides (see Figure 2.3.10.).
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.12.Ceiling Membrane Rating
(1) Where the fire-resistance rating of a ceiling assembly is to be determined on the basis of the membrane only and not
of the complete assembly, the ratings may be determined from Table 2.3.12., provided no openings described in Articles
2.3.10. and 2.3.11. are located within the ceiling membrane.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.3.12.
Fire-Resistance Rating for Ceiling Membranes
Description of Membrane Fire-Resistance Rating, min
15.9 mm Type X gypsum board with ≥ 75 mm mineral wool batt insulation above board 30
19 mm gypsum-sand plaster on metal lath 30
Double 14.0 mm Douglas Fir plywood phenolic bonded 30
Double 12.7 mm Type X gypsum board 45
25 mm gypsum-sand plaster on metal lath 45
Double 15.9 mm Type X gypsum board 60
32 mm gypsum-sand plaster on metal lath 60
Column 1 2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.13.Membrane Penetrations in Combustible and Noncombustible Construction
(1) Where a wall, floor or roof assembly is assigned a fire-resistance rating on the basis of this Subsection and includes
a membrane or membranes described in Table 2.3.4.A., 2.3.4.B., 2.3.4.C., 2.3.4.D. or 2.3.12., penetrations of the
membrane or membranes must be fire stopped in conformance with the applicable requirements in Article 3.1.9.1. or
Sentence 9.10.9.6.(1) of Division B of the Building Code.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.3.14.Beams
(1) Where a steel beam is included with an open-web steel joist and is protected by the same continuous ceiling, the
beam is assumed to have a fire-resistance rating equal to that assigned to the rest of the assembly.
(2) The ratings in this Subsection assume that the construction to which the beam is related is a normal one and does not
carry unusual loads from the floor or slab above.
2.3.15.Wired Glass Assembly Support
(1) Openings in a vertical fire separation having a fire-resistance rating of not more than 1 h are allowed to be protected
by wired glass assemblies, provided the wired glass is
(a) not less than 6 mm thick,
(b) reinforced by a steel wire mesh in the form of diamonds, squares or hexagons having dimensions of
(i) approximately 25 mm across the flats, using wire of not less than 0.45 mm diameter, or
(ii) approximately 13 mm across the flats, using wire of not less than 0.40 mm diameter, the wire to be centrally
embedded during manufacture and welded or intertwined at each intersection,
(c) set in fixed steel frames with metal not less than 1.35 mm thick and providing a glazing stop of not less than 20 mm
on each side of the glass, and
(d) limited in area so that
(i) individual panes are not more than 0.84 m2, with neither height nor width more than 1.4 m, and
(ii) the area not structurally supported by mullions is not more than 7.5 m2.
(2) It is intended that the structural mullions referred to in Subclause (1)(d)(ii) will not distort or be displaced to the
extent that there would be a failure of the wired glass closure during the period for which a closure in the fire separation
would be expected to function. Hollow structural steel tubing not less than 100 mm square filled with a Portland cement-
based grout will satisfy the intent of the Subclause.
Page 24 • SB-2
2024MMAH Supplementary Standard SB-2
2.4. Solid Wood Walls, Floors and Roofs
2.4.1.Minimum Thickness
(1) The minimum thickness of solid wood walls, floors and roofs for fire-resistance ratings from 30 min to 1.5 h is
shown in Table 2.4.1.
Table 2.4.1.
Minimum Thickness of Solid Wood Walls, Roofs and Floors, (1)(2) mm
Fire-Resistance Rating
Type of Construction
30 min 45 min 1h 1.5 h
Solid wood floor with building paper and finish flooring on top(3) 89 114 165 235
Solid wood, splined or tongued and grooved floor with building paper
64 76 — —
and finish flooring on top(4)
Solid wood walls of loadbearing vertical plank(3) 89 114 140 184
Solid wood walls of non-loadbearing horizontal plank(3) 89 89 89 140
Column 1 2 3 4 5
Notes to Table 2.4.1.:
(1) See CSA O141, "Softwood lumber", for sizes.
(2) The fire-resistance ratings and minimum dimensions for floors also apply to solid wood roof decks of comparable thickness with finish
roofing material.
(3) The assembly shall consist of 38 mm thick members on edge fastened together with 101 mm common wire nails spaced not more
than 406 mm o.c. and staggered in the direction of the grain.
(4) The floor shall consist of 64 mm by 184 mm wide planks either tongued and grooved or with 19 mm by 38 mm splines set in grooves
and fastened together with 88 mm common nails spaced not more than 406 mm o.c.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.4.2.Increased Fire-Resistance Rating
(1) The fire-resistance rating of the assemblies described in Table 2.4.1. may be increased by 15 min if one of the
following finishes is applied on the fire-exposed side:
(a) 12.7 mm thick gypsum board,
(b) 20 mm thick gypsum-sand plaster on metal lath, or
(c) 13 mm thick gypsum-sand plaster on 9.5 mm gypsum lath.
(2) Fastening of the plaster to the wood structure shall conform to Subsection 2.3.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.4.3.Supplementary Ratings
(1) Supplementary ratings based on tests are included in Table 2.4.3. The ratings given shall apply to construction that
conform in all details with the descriptions given.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.4.3.
Fire-Resistance Rating of Non-Loadbearing Built-up Solid Wood Partitions(1)
Actual Overall Thickness,
Construction Details Fire-Resistance Rating
mm
Solid panels of wood boards 64 mm to 140 mm wide grooved and joined with
wood splines, nailed together, boards placed vertically with staggered joints, 58 30 min
3 boards thick
Solid panels with 4 mm plywood facings(2) glued to 46 mm solid wood core of
glued, tongued and grooved construction for both sides and ends of core 54 1h
pieces with tongued and grooved rails in the core about 760 mm apart
Column 1 2 3
Notes to Table 2.4.3.:
(1) The ratings and notes are taken from "Fire Resistance Classifications of Building Constructions", Building Materials and Structures
Report BMS 92, National Bureau of Standards, Washington, 1942.
(2) Ratings for plywood faced panel are based on phenolic resin glue being used for gluing facings to wood frames. If other types of glue
are used for this purpose, the ratings apply if the facings are nailed to the frames in addition to being glued.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.5.1.Minimum Thickness
(1) The minimum thickness of solid plaster partitions for fire-resistance ratings from 30 min to 4 h is shown in
Table 2.5.1.
Table 2.5.1.
Minimum Thickness of Non-Loadbearing Solid Plaster Partitions, mm
Fire-Resistance Rating
Type of Plaster on Metal Lath(1)
30 min 45 min 1h 1.5 h 2h 3h 4h
Portland cement-sand(2) or Portland cement-lime-sand 50(3) — — — — — —
Gypsum-sand 50(3) 50(3) 64 — — — —
Gypsum-vermiculite, gypsum-perlite, Portland cement-vermiculite or
50(3) 50(3) 50(3) 58 64 83 102
Portland cement-perlite
Column 1 2 3 4 5 6 7 8
Notes to Table 2.5.1.:
(1) Metal lath shall be expanded metal lath or welded woven wire fabric supported on 19 mm vertical light steel studs spaced not more
than 610 mm o.c. Plaster shall be applied to both sides of the lath.
(2) For mixture of Portland cement-sand plaster, see Sentence 1.7.2.(2).
(3) CSA A82.30-M, "Interior Furring, Lathing and Gypsum Plastering", does not permit solid plaster partitions less than 50 mm thick.
Page 26 • SB-2
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2.6.1.Minimum Thickness of Protective Covering
(1) The minimum thickness of protective covering to steel columns is shown in Tables 2.6.1.A. to 2.6.1.F. for fire-
resistance ratings from 30 min to 4 h.
Table 2.6.1.A.
Minimum Thickness of Concrete or Masonry Protection to Steel Columns, mm
Fire-Resistance Rating
Description of Cover
30 min 45 min 1h 1.5 h 2h 3h 4h
Monolithic concrete
Type S concrete(1) (column spaces filled)(2) 25 25 25 25 39 64 89
Type N or L concrete(1) (column spaces filled)(2) 25 25 25 25 32 50 77
Concrete masonry units(3) or precast reinforced concrete units
Type S concrete (column spaces not filled) 50 50 50 50 64 89 115
Type N or L concrete (column spaces not filled) 50 50 50 50 50 77 102
Clay or shale brick(4) (column spaces filled)(2) 50 50 50 50 50 64 77
Clay or shale brick(4) (column spaces not filled) 50 50 50 50 50 77 102
Hollow clay tile(5) (column spaces filled)(2) 50(6) 50(6) 50(6) 50(6) (7) (7) (7)
Hollow clay tile(5) (column spaces not filled) 50(6) 50(6) 50(6) — — — —
Column 1 2 3 4 5 6 7 8
Notes to Table 2.6.1.A.:
(1) Applies to cast-in-place concrete reinforced with 5.21 mm diam wire wrapped around column spirally 200 mm o.c., or 1.57 mm diam
wire mesh with 100 mm by 100 mm openings.
(2) The space between the protective covering and the web or flange of the column shall be filled with concrete, cement mortar or a
mixture of cement mortar and broken bricks.
(3) Concrete masonry shall be reinforced with 5.21 mm diam wire or wire mesh with 1.19 mm diam wire and 10 mm by 10 mm openings,
laid in every second course.
(4) Brick cover 77 mm thick or less shall be reinforced with 2.34 mm diam wire or 1.19 mm diam wire mesh with 10 mm by 10 mm
openings, laid in every second course.
(5) Hollow clay tiles and masonry mortar shall be reinforced with 1.19 mm diam wire mesh with 10 mm by 10 mm openings, laid in every
horizontal joint and lapped at corners.
(6) Hollow clay tiles shall conform to CAN/CSA-A82, “Fired masonry brick made from clay or shale".
(7) 50 mm nominal hollow clay tile, reinforced with 1.19 mm diam wire mesh with 10 mm by 10 mm openings laid in every horizontal joint
and covered with 19 mm gypsum-sand plaster and with limestone concrete fill in column spaces, has a 4 h fire-resistance rating.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.6.1.B.
Minimum Thickness of Plaster Protection to Steel Columns, mm
Fire-Resistance Rating(1)(2)
Description
30 min 45 min 1h 1.5 h 2h 3h 4h
Gypsum-sand plaster on 9.5 mm gypsum lath(3) 13 13 13 20 — — —
Gypsum-perlite or vermiculite plaster on 9.5 mm gypsum lath(3) 13 13 13 20 25 — —
Gypsum perlite or vermiculite plaster on 12.7 mm gypsum lath(3) 13 13 13 20 25 32 50
Gypsum perlite or vermiculite plaster on double 12.7 mm gypsum lath(3) 13 13 13 20 25 25 32
Portland cement-sand plaster on metal lath(4)(5) 25 25 25 — — — —
Column 1 2 3 4 5 6 7 8
Notes to Table 2.6.1.B.:
(1) Fire-resistance ratings of 30 min and 45 min apply to columns whose M/D ratio is 30 or greater. Fire-resistance ratings greater than
45 min apply to columns whose M/D ratio is greater than 60. Where the M/D ratio is between 30 and 60 and the required
fire-resistance rating is greater than 45 min, the total thickness of protection specified in the Table shall be increased by 50%. (To
determine M/D, refer to Article 2.6.4.)
(2) Where the thickness of plaster over gypsum lath is 25 mm or more, wire mesh with 1.57 mm diam wire and openings not exceeding
50 mm by 50 mm shall be placed midway in the plaster.
(3) Lath held in place by 1.19 mm diam wire wrapped around lath 450 mm o.c.
(4) Expanded metal lath 1.36 kg/m2 fastened to 9.5 mm by 19 mm steel channels held in vertical position around column by 1.19 mm
diam wire ties.
(5) For mixture of Portland cement-sand plaster, see Sentence 1.7.2.(2).
Table 2.6.1.C.
Minimum Thickness of Gypsum-Sand Plaster on Metal Lath Protection to Steel Columns, mm
Fire-Resistance Rating
M/D(1)
30 min 45 min 1h 1.5 h 2h 3h
30 to 60 16 16 32 — — —
over 60 to 90 16 16 16 32 — —
over 90 to 120 16 16 16 25 39 —
over 120 to 180 16 16 16 16 25 —
over 180 16 16 16 16 25 39
Column 1 2 3 4 5 6 7
Notes to Table 2.6.1.C.:
(1) To determine the M/D ratio, refer to Article 2.6.4.
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2024MMAH Supplementary Standard SB-2
Table 2.6.1.D.
Minimum Thickness of Gypsum-Perlite or Gypsum-Vermiculite Plaster on Metal Lath Protection to Steel Columns, mm
Fire-Resistance Rating
M/D(1)
30 min 45 min 1h 1.5 h 2h 3h 4h
30 to 60 16 16 20 32 35 — —
over 60 to 90 16 16 16 20 26 35 45
over 90 to 120 16 16 16 16 26 35 45
over 120 to 180 16 16 16 16 20 32 35
over 180 16 16 16 16 16 26 35
Column 1 2 3 4 5 6 7 8
Notes to Table 2.6.1.D.:
(1) To determine the M/D ratio, refer to Article 2.6.4.
Table 2.6.1.E.
Steel Columns with Sheet-Steel Membrane and Insulation as Shown in Figures 2.6.1.A. and 2.6.1.B.
Steel Fire-Resistance
Type of Protection Fastening(2) Insulation
Thickness,(1) mm Rating
No. 8 sheet-metal screws
See Figure 2.6.1.A. 0.51 50 mm mineral wool batts(3) 45 min
9.5 mm long, 200 mm o.c.
Self-threading screws or No. 8 2 layers 12.7 mm gypsum
See Figure 2.6.1.B. 0.64 1.5 h
sheet-metal screws, 600 mm o.c. board
No. 8 sheet-metal screws, 75 mm mineral wool batts,(3)
See Figure 2.6.1.A. 0.64 2h
9.5 mm long, 200 mm o.c. 12.7 mm gypsum board
Crimped joint or No. 8 sheet-metal 2 layers 15.9 mm gypsum
See Figure 2.6.1.B. 0.76 2h
screws, 300 mm o.c. board
Column 1 2 3 4 5
Notes to Table 2.6.1.E.:
(1) Minimum thickness, galvanized or wiped-zinc-coated sheet-steel.
(2) Sheet-steel shall be securely fastened to the floor and superstructure, or where sheet-steel cover does not extend floor to floor, fire
stopping shall be provided at the level where sheet-steel protection ends. In the latter case, an alternate type of fire protection shall be
applied between the fire stopping and the superstructure.
(3) Conforming to CAN/ULC-S702.1, "Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1: Material Specification", Type 1A,
minimum density 30 kg/m3: column section and batts wrapped with 25 mm mesh chicken wire.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 2.6.1.F.
Minimum M/D Ratio for Steel Columns Covered With Type X Gypsum Board Protection(1)
Minimum Thickness of Type X Gypsum Fire-Resistance Rating
Board Protection(2), mm 1h 1.5 h 2h 3h
12.7 75 — — —
15.9 55 — — —
25.4 35 60 — —
28.6 35 50 — —
31.8 35 40 75 —
38.1 35 35 55 —
41.3 35 35 45 —
44.5 35 35 35 —
47.6 35 35 35 —
50.8 35 35 35 75
63.5 35 35 35 45
Column 1 2 3 4 5
Notes to Table 2.6.1.F.:
(1) To determine the M/D ratio, refer to Article 2.6.4.
(2) See Article 2.6.5.
Figure 2.6.1.A.
Column Protected by Sheet-Steel Membrane, Gypsum Board and Mineral-Wool Insulation
Page 30 • SB-2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Figure 2.6.1.B.
Column Protected by Sheet-Steel Membrane and Gypsum Board
2.6.2.Hollow Unit Masonry Columns
(1) For hollow-unit masonry column protection, the thickness shown in Tables 2.6.1.A. to 2.6.1.D. is the equivalent
thickness as described in Subsection 1.6.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.6.3.Effect of Plaster
(1) The effect on fire-resistance ratings of the addition of plaster to masonry and monolithic concrete column protection
is described in Subsection 1.7.
2.6.4.Determination of M/D Ratio
(1) The ratio M/D to which reference is made in Tables 2.6.1.B., 2.6.1.C., 2.6.1.D. and 2.6.1.F. shall be found by
dividing "M," the mass of the column in kilograms per metre by "D," the heated perimeter of the steel column section in
metres.
(2) The heated perimeter "D" of steel columns, shown as the dashed line in Figure 2.6.4.A., shall be equal to 2 (B+H) in
Examples (1) and (2), and 3.14B in Example (3). In Figure 2.6.4.B., the heated perimeter "D" shall be equal to 2 (B+H).
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Figure 2.6.4.A.
Example (1), Standard or Wide-Flange Beam,
Example (2), Hollow Structural Section (Rectangular or Square),
Example (3), Hollow Structural Section (Round)
1 1
3 3
B
2 4 2
1 structural member
steel studs
1 layer 2 layers gypsum board (Type X)
3 steel corner bead
H
2 tie wire
sheet metal angle
4 1 1
3 6 3
4 2 2
3 layers 4 layers EG01230B
Figure 2.6.4.B.
Columns Protected by Type X Gypsum Board Without Sheet-Steel Membrane
2.6.5.Attachment of Gypsum Board
(1) Where Type X gypsum board is used to protect a steel column without an outside sheet-steel membrane, the method
of gypsum board attachment to the column shall be as shown in Figure 2.6.4.B. and shall meet the construction details
described in Sentences (2) to (7).
(2) The Type X gypsum board shall be applied vertically without horizontal joints.
(3) The first layer of gypsum board shall be attached to steel studs with screws spaced not more than 610 mm o.c. and
other layers of gypsum board shall be attached to steel studs and steel corner beads with screws spaced at a maximum of
305 mm o.c. Where a single layer of gypsum board is used, attachment screws shall be spaced not more than
305 mm o.c.
(4) Steel tie wires spaced at a maximum of 610 mm o.c. shall be used to secure the second last layer of gypsum board in
3- and 4-layer systems.
(5) Studs shall be fabricated of galvanized steel not less than 0.53 mm thick and not less than 41.3 mm wide, with legs
not less than 33.3 mm long and shall be 12.7 mm less than the assembly height.
Page 32 • SB-2
2024MMAH Supplementary Standard SB-2
(6) Corner beads shall
(a) be fabricated of galvanized steel that is not less than 0.41 mm thick,
(b) have legs not less than 31 mm long,
(c) be attached to the gypsum board or stud with 25.4 mm screws spaced not more than 305 mm o.c., and
(d) have the attaching fasteners penetrate either another corner bead in multiple layer assemblies or the steel stud
member.
(7) In a 4-layer system, metal angles shall be fabricated of galvanized steel and shall be not less than 0.46 mm thick
with legs not less than 51 mm long.
2.6.6.Concrete Filled Hollow Steel Columns
(1) A fire-resistance rating, R, is permitted to be assigned to concentrically loaded hollow steel columns that are filled
with plain concrete, steel-fibre reinforced concrete or bar-reinforced concrete, that are fabricated and erected within the
tolerances stipulated in CSA S16, "Design of steel structures", and that comply with Sentences (2) and (3), provided:
C ≤ Cmax
where
C = axial compressive force due to dead and live loads without load factors, kN,
𝑎 (𝑓𝑐′ + 20) 𝐷2.5 2
Cmax = ( )
𝑅 (𝐾𝐿 – 1000)
but shall not exceed
1.0 Cr′ for plain concrete filling (PC),
1.1 Cr′ for steel-fibre reinforced concrete filling (FC), and
1.7 Cr′ for bar-reinforced concrete filling (RC),
where
Cr′ = 0.85ϕ𝑐 𝑓𝑐′ 𝐴𝑐 λ−2 −4 − 0.5λ−2 ]
𝑐 [√1 + 0.25λ𝑐 𝑐
where
a = constant obtained from Table 2.6.6.A.,
𝑓𝑐′ = specified compressive strength of concrete in accordance with CSA A23.3, "Design of concrete
structures", MPa,
rc = radius of gyration of the concrete area,
Ac = area of concrete, mm2,
D = outside diameter of a round column or outside width of a square column, mm,
Ec = initial elastic modulus for concrete, considering the effects of long-term load for normal-weight
𝑆
concrete = (1 + ) 2500√fc′ , where fc′ is expressed in MPa, S is the short-term load, and T is the total
𝑇
load on the column,
R = specified fire-resistance rating, min,
KL = effective length of column as defined in CSA S16, "Design of steel structures", mm,
𝐾𝐿 𝑓′
λc = 𝑟 √𝜋2𝑐𝐸 , and
𝑐 𝑐
ϕc = 0.60
subject to the validity limits specified in Table 2.6.6.B.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
(2) A pair of steam vent holes shall be provided at each end of the hollow steel column and at each intermediate floor
level, and the holes shall be
(a) not less than 13 mm in diameter,
(b) located on opposite faces, 150 mm above or below a base plate, cap plate or concrete slab,
(c) orientated so that adjacent pairs are perpendicular, and
(d) not obstructed by other building elements.
(3) Load application and reaction shall be through end bearing in accordance with CSA S16, "Design of steel
structures".
Table 2.6.6.A.
Values of Constant "a"
Filling Type Concrete Type(1) Steel Reinforcement Circular Columns Square Columns
PC S n/a 0.070 0.060
FC S ≈ 2% 0.075 0.065
RC S 1.5% – 3% 0.080 0.070
RC S 3% – 5% 0.085 0.075
PC N n/a 0.080 0.070
FC N ≈ 2% 0.085 0.075
RC N 1.5% – 3% 0.090 0.080
RC N 3% – 5% 0.095 0.085
Column 1 2 3 4 5
Notes to Table 2.6.6.A.:
(1) See Subsection 1.4.
Table 2.6.6.B.
Validity Limits
Type of Concrete Filling
Parameter
PC FC RC
𝑓𝑐′ (MPa) 20 to 40 20 to 55 20 to 55
D (round) (mm) 140 to 410 120 to 410 165 to 410
D (square) (mm) 140 to 305 102 to 305 175 to 305
≈ 2% of the concrete mix 1.5% to 5% of cross-sectional
Reinforcement (%) n/a
by mass area(1)
Concrete Cover (mm) n/a n/a ≥ 25
R (min) ≤ 120 ≤ 180 ≤ 180
KL (mm) 2 000 to 4 000 2 000 to 4 500 2 000 to 4 500
Class(2) 1, 2 or 3 1, 2 or 3 1, 2 or 3
Column 1 2 3 4
Notes to Table 2.6.6.B.:
(1) Limits on size, number and spacing of bars and ties in accordance with CSA A23.3, "Design of concrete structures".
(2) Classification of sections in accordance with CSA S16, "Design of steel structures".
Page 34 • SB-2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.7.1.Minimum Thickness of Protective Covering
(1) The minimum thickness of protective covering on steel beams exposed to fire on 3 sides for fire-resistance ratings
from 30 min to 4 h is shown in Table 2.7.1.
Table 2.7.1.
Minimum Thickness of Cover to Individual Protected Steel Beams, (1) mm
Fire-Resistance Rating
Description of Cover
30 min 45 min 1h 1.5 2h 3h 4h
Type S concrete(2) (beam spaces filled solid) 25 25 25 25 32 50 64
Type N or L concrete(2) (beam spaces filled solid) 25 25 25 25 25 39 50
Gypsum-sand plaster on 9.5 mm gypsum lath(3) 13 13 13 20 — — —
Gypsum-perlite or vermiculite plaster on 9.5 mm gypsum lath(3) 13 13 13 13 25 — —
Gypsum-perlite or gypsum-vermiculite on 12.7 mm gypsum lath(3) 13 13 13 20 25 39 50
Gypsum-perlite or vermiculite plaster on double 12.7 mm gypsum
13 13 13 20 25 25 39
lath(3)
Portland cement-sand on metal lath(4) 23 23 23 — — — —
Gypsum-sand on metal lath(4) (plaster in contact with lower flange) 16 20 25 39 — — —
Gypsum-sand on metal lath with air gap between plaster and lower
16 16 16 25 25 — —
flange(4)
Gypsum-perlite or gypsum-vermiculite on metal lath(4) 16 16 16 23 23 35 48(5)
Column 1 2 3 4 5 6 7 8
Notes to Table 2.7.1.:
(1) Where the thickness of plaster finish applied over gypsum lath is 26 mm or more, the plaster shall be reinforced with wire mesh with
1.57 mm diam wire and 50 mm by 50 mm openings placed midway in the plaster.
(2) Applies to cast-in-place concrete reinforced by 5.21 mm diam wire spaced 200 mm o.c. or 1.57 mm diam wire mesh with 100 mm by
100 mm openings.
(3) Lath held in place by 1.18 mm diam wire wrapped around the gypsum lath 450 mm o.c.
(4) Expanded metal lath 1.63 kg/m2 fastened to 9.5 mm by 19 mm steel channels held in position by 1.19 mm diam wire.
(5) Plaster finish shall be reinforced with wire mesh with 1.57 mm diam wire and 50 mm by 50 mm openings placed midway in the plaster.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.7.2.Types of Concrete
(1) Concrete is referred to as Type S, N or L, depending on the nature of the aggregate used. This is described in
Article 1.4.1.
2.7.3.Effect of Plaster
(1) The effect on fire-resistance ratings of the addition of plaster finish to concrete or masonry beam protection is
described in Article 1.7.1.
2.7.4.Exceptions
(1) The fire resistance of protected steel beams depends on the means used to hold the protection in place. Because of
the importance of this factor, no rating has been assigned in Table 2.7.1. to masonry units used as protective cover to steel
beams. These ratings, however, may be determined on the basis of comparison with column protection at the discretion
of the authority having jurisdiction, if satisfactory means of fastening are provided.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.7.5.Beam Protected by a Membrane
(1) A steel beam or steel joist assembly that is entirely above a horizontal ceiling membrane will be protected from fire
below the membrane and will resist structural collapse for a period equal to the fire-resistance rating determined in
conformance with Subsection 2.3. The support for this membrane shall be equivalent to that described in Subsection 2.3.
The rating on this basis shall not exceed 1.5 h.
2.8.1.Minimum Dimensions
(1) Minimum dimensions for reinforced concrete columns and minimum concrete cover for vertical steel reinforcement
are obtained from Articles 2.8.2. to 2.8.5., taking into account the type of concrete, the effective length of the column and
the area of the vertical reinforcement.
2.8.2.Method
(1) The minimum dimension, t, in millimetres, of a rectangular reinforced concrete column shall be equal to
(a) 75 f (R + 1) for all Types L and L40S concrete,
(b) 80 f (R + 1) for Type S concrete when the design condition of the concrete column is defined in the second and
fourth columns of Table 2.8.2.,
(c) 80 f (R + 0.75) for Type N concrete when the design condition of the concrete column is defined in the second and
fourth columns of Table 2.8.2., and
(d) 100 f (R + 1) for Types S and N concrete when the design condition of the concrete column is defined in the third
column of Table 2.8.2.
where
f = the value shown in Table 2.8.2.,
R = the required fire-resistance rating in hours,
k = the effective length factor obtained from CSA A23.3, "Design of concrete structures",
h = the unsupported length of the column in metres, and
p = the area of vertical reinforcement in the column as a percentage of the column area.
(2) The diameter of a round column shall be not less than 1.2 times the value "t" determined in Sentence (1) for a
rectangular column.
Page 36 • SB-2
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2024MMAH Supplementary Standard SB-2
Table 2.8.2.
Values of Factor "f"(1)
Values of Factor f to be Used in Applying Article 2.8.2.
Where kh is more than 3.7 m but not more than 7.3 m
Overdesign Factor(2)
Where kh is not more than 3.7 m t is not more than 300 mm,
All other cases(4)
p is not more than 3%(3)
1.00 1.00 1.20 1.00
1.25 0.90 1.10 0.90
1.50 0.83 1.00 0.83
Column 1 2 3 4
Notes to Table 2.8.2.:
(1) For conditions that do not fall within the limits described in Table 2.8.2., further information may be obtained from Reference (7) in
Subsection 6.1.
(2) Overdesign factor is the ratio of the calculated load carrying capacity of the column to the column strength required to carry the
specified loads determined in conformance with CSA A23.3, "Design of concrete structures".
(3) Where the factor "f" results in a "t" greater than 300 mm, the appropriate factor "f" for "All other cases" shall be applicable.
(4) Where "p" is equal to or less than 3% and the factor "f" results in a "t" less than 300 mm, the minimum thickness shall be 300 mm.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.8.3.Minimum Thickness of Concrete Cover
(1) Where the required fire-resistance rating of a concrete column is 3 h or less, the minimum thickness in millimetres
of concrete cover over vertical steel reinforcement shall be equal to 25 times the number of hours of fire resistance
required or 50 mm, whichever is less.
(2) Where the required fire-resistance rating of a concrete column is greater than 3 h, the minimum thickness in
millimetres of concrete cover over vertical steel reinforcement shall be equal to 50 plus 12.5 times the required number of
hours of fire resistance in excess of 3 h.
(3) Where the concrete cover over vertical steel required in Sentence (2) exceeds 62.5 mm, wire mesh reinforcement
with 1.57 mm diameter wire and 100 mm openings shall be incorporated midway in the concrete cover to retain the
concrete in position.
2.8.4.Minimum Requirements
(1) The structural design standards may require minimum column dimensions or concrete cover over vertical steel
reinforcement differing from those obtained in Sentences 2.8.2.(1) and (2). Where a difference occurs, the greater
dimension shall govern.
2.8.5.Addition of Plaster
(1) The addition of plaster finish to the concrete column may be taken into account in determining the cover over
vertical steel reinforcement by applying the multiplying factors described in Subsection 1.7. The addition of plaster shall
not, however, justify any decrease in the minimum column sizes shown.
2.8.6.Built-in Columns
(1) The fire-resistance rating of a reinforced concrete column that is built into a masonry or concrete wall so that not
more than one face may be exposed to the possibility of fire at one time may be determined on the basis of cover to
vertical reinforcing steel alone. In order to meet this condition, the wall shall conform to Subsection 2.1. for the fire-
resistance rating required.
2.9.1.Minimum Cover Thickness
(1) The minimum thickness of cover over principal steel reinforcement in reinforced concrete beams is shown in
Table 2.9.1. for fire-resistance ratings from 30 min to 4 h where the width of the beam or joist is at least 100 mm.
Table 2.9.1.
Minimum Cover to Principal Steel Reinforcement in Reinforced Concrete Beams, mm
Fire-Resistance Rating
Type of Concrete
30 min 45 min 1h 1.5 h 2h 3h 4h
Type S, N or L 20 20 20 25 25 39 50
Column 1 2 3 4 5 6 7 8
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.9.2.Maximum Rating
(1) No rating over 2 h may be assigned on the basis of Table 2.9.1. to a beam or joist where the average width of the
part that projects below the slab is less than 140 mm, and no rating over 3 h may be assigned where the average width of
the part that projects below the slab is less than 165 mm.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.9.3.Beam Integrated in Floor or Roof Slab
(1) For the purposes of these ratings, a beam may be either independent of or integral with a floor or roof slab assembly.
2.9.4.Minimum Thickness
(1) Where the upper extension or top flange of a joist or T-beam in a floor assembly contributes wholly or partly to the
thickness of the slab above, the total thickness at any point shall be not less than the minimum thickness described in
Table 2.2.1.A. for the fire-resistance rating required.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.9.5.Effect of Plaster
(1) The addition of plaster finish to a reinforced concrete beam may be taken into account in determining the cover over
principal reinforcing steel by applying the multiplying factors described in Subsection 1.7.
Page 38 • SB-2
2.10.1.Minimum Cross-Sectional Area and Thickness of Cover
(1) The minimum cross-sectional area and thickness of concrete cover over steel tendons in prestressed concrete beams
for fire-resistance ratings from 30 min to 4 h are shown in Table 2.10.1.
Table 2.10.1.
Minimum Thickness of Concrete Cover Over Steel Tendons in Prestressed Concrete Beams,(1) mm
Fire-Resistance Rating
Type of Concrete Area of Beam, cm2
30 min 45 min 1h 1.5 h 2h 3h 4h
260 to 970 25 39 50 64 — — —
Type S or N Over 970 to 1 940 25 26 39 45 64 — —
Over 1 940 25 26 39 39 50 77 102
Type L Over 970 25 25 25 39 50 77 102
Column 1 2 3 4 5 6 7 8 9
Notes to Table 2.10.1.:
(1) Where the thickness of concrete cover over the tendons exceeds 64 mm, a wire mesh reinforcement with 1.57 mm diam wire and
100 mm by 100 mm openings shall be incorporated in the beams to retain the concrete in position around the tendons. The mesh
reinforcement shall be located midway in the cover.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.10.2.Minimum Cover Thickness
(1) The cover for an individual tendon shall be the minimum thickness of concrete between the surface of the tendon
and the fire-exposed surface of the beam, except that for ungrouted ducts the assumed cover thickness shall be the
minimum thickness of concrete between the surface of the duct and the surface of the beam. For beams in which several
tendons are used, the cover is assumed to be the average of the minimum cover of the individual tendons. The cover for
any individual tendon shall be not less than half the value given in Table 2.10.1. nor less than 25 mm.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.10.3.Applicability of Ratings
(1) The ratings in Table 2.10.1. apply to a beam that is either independent of or integral with a floor or roof slab
assembly. Minimum thickness of slab and minimum cover to steel tendons in prestressed concrete slabs are contained in
Subsection 2.2.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2.10.4.Effect of Plaster
(1) The addition of plaster finish to a prestressed concrete beam may be taken into account in determining the cover
over steel tendons by applying the multiplying factors described in Subsection 1.7.
2.10.5.Minimum Cover
(1) Except as provided in Sentence (2), in unbonded post- tensioned prestressed concrete beams, the concrete cover to
the tendon at the anchor shall be not less than 15 mm greater than the minimum required away from the anchor. The
concrete cover to the anchorage bearing plate and to the end of the tendon, if it projects beyond the bearing plate, shall be
not less than 25 mm.
(2) The requirements in Sentence (1) do not apply to those portions of beams not likely to be exposed to fire (such as
the ends and the tops of flanges of beams immediately below slabs).
2.11.1.Determination of Ratings
(1) The calculation methods described in this Subsection are intended to be used to determine fire-resistance ratings for
structural mass timber elements on the basis of the elements being subjected to the standard fire exposure conditions
described in CAN/ULC-S101, “Standard Method of Fire Endurance Tests of Building Construction and Materials”.
(2) Loadbearing mass timber members, such as beams and columns, subjected to the conditions described in
Sentence (1) are assigned a fire-resistance rating that relates to the time at which the applied load is no longer sustained.
(3) Mass timber wall, floor and roof assemblies subjected to the conditions described in Sentence (1) are assigned a fire-
resistance rating that relates to the lesser of the times at which
(a) an average temperature rise of 140°C or a maximum temperature rise of 180°C at any individual location is recorded
on the unexposed side of the assembly,
(b) there is passage of flame or gases hot enough to ignite cotton pads through the unexposed side of the assembly, or
(c) the applied load is no longer sustained, where the assembly is loadbearing.
2.11.2.Applicability of Calculation Methods
(1) Method A described in Article 2.11.3. applies to glued-laminated timber beams and columns required to have fire-
resistance ratings greater than those afforded under the provisions of Article 3.1.4.6.
(2) Method B described in Article 2.11.4. applies to mass timber elements, including solid sawn timber and glued-
laminated timber beams and columns, required to have fire-resistance ratings greater than those afforded under the
provisions of Article 3.1.4.6.
(3) The calculation methods described in Articles 2.11.3. and 2.11.4. are separate and independent methods that use
different approaches to determine fire-resistance ratings for mass timber elements.
Page 40 • SB-2
2.11.3.Method A for Glued-Laminated Timber Beams and Columns
(1) The fire-resistance rating of glued-laminated timber beams and columns in minutes is permitted to be taken as equal
to
(a) 0.1 fB [4 - 2(B/D)] for beams which may be exposed to fire on 4 sides,
(b) 0.1 fB [4 - (B/D)] for beams which may be exposed to fire on 3 sides,
(c) 0.1 fB [3 - (B/D)] for columns which may be exposed to fire on 4 sides, and
(d) 0.1 fB [3 - (B/2D)] for columns which may be exposed to fire on 3 sides,
where
f = the load factor shown in Figure 2.11.3.A.,
B = the full dimension of the smaller side of a beam or column in millimetres before exposure to fire
(see Figure 2.11.3.B.),
D = the full dimension of the larger side of a beam or column in millimetres before exposure to fire
(see Figure 2.11.3.B.),
k = the effective length factor obtained from CSA O86, "Engineering design in wood",
L = the unsupported length of a column in millimetres.
(2) The factored resistance of a beam or column shall be determined by using the specified strengths in CSA O86,
"Engineering design in wood".
Figure 2.11.3.A.
Factors to Compensate for Partially Loaded Columns and Beams
Notes to Figure 2.11.3.A.:
(1) In the case of beams, use bending moment in place of load.
(2) See Sentence 2.11.3.(2).
2024MMAH Supplementary Standard SB-2
Figure 2.11.3.B.
Full Dimensions of Glued-Laminated Beams and Columns
2.11.4.Method B for Mass Timber Elements
(1) The fire-resistance rating of structural mass timber members, such as beams and columns constructed of glued-
laminated timber, solid sawn timber, or structural composite lumber, is permitted to be determined using the calculation
method described in Annex B, Fire resistance of large cross-section wood elements, of CSA O86, “Engineering design in
wood”.
(2) Except as provided in Sentences (3) to (6), the fire-resistance rating of mass timber wall, floor and roof assemblies,
including those constructed of cross-laminated timber, is permitted to be determined using the calculation method
described in Annex B, Fire resistance of large cross-section wood elements, of CSA O86, “Engineering design in wood”.
(3) Except as provided in Sentence (4), the assemblies described in Sentence (2) shall be protected to maintain the
integrity and thermal insulation properties of the assembly for the time period corresponding to the calculated fire-
resistance rating as follows:
(a) except as provided in Clause (b), for floor and roof assemblies, by applying at least one of the following layers to the
unexposed surface of the assembly:
(i) OSB or plywood not less than 12.5 mm thick, with the joints in the layer staggered relative to those in the
assembly,
(ii) concrete topping not less than 38 mm thick, or
(iii) gypsum-concrete topping not less than 25 mm thick,
(b) for plank decking designed in accordance with Clause B.10 of CSA O86, “Engineering design in wood”, by
applying at least one of the layers described in Clause B.10.4 of CSA O86 to the unexposed surface of the assembly,
Page 42 • SB-2
2024MMAH Supplementary Standard SB-2
(c) for interior wall assemblies, by applying at least one of the following layers to at least one side of the assembly, with
the joints in the layer staggered relative to those in the assembly:
(i) OSB or plywood not less than 12.5 mm thick, or
(ii) Type X gypsum board not less than 12.7 mm thick, and
(d) for exterior wall assemblies, by applying at least one of the following layers to at least one side of the assembly,
with the joints in the layer staggered relative to those in the assembly:
(i) OSB or plywood not less than 12.5 mm thick,
(ii) Type X gypsum board not less than 12.7 mm thick,
(iii) gypsum sheathing not less than 12.7 mm thick applied to the exterior (unexposed) side of the assembly, or
(iv) rock or slag insulation sheathing not less than 50 mm thick applied to the exterior (unexposed) side of the
assembly.
(4) For wall, floor and roof assemblies constructed of cross-laminated timber, the joints between cross-laminated timber
panels in the assembly need not be protected in accordance with Sentence (3), provided the joints are either lapped or
splined to maintain the integrity and thermal insulation properties of the assembly for the time period corresponding to the
calculated fire-resistance rating. (See Figure 2.11.4.(4).)
Figure 2.11.4.(4)
Joints Between Cross-Laminated Timber Panels in Wall, Floor and Roof Assemblies
(5) For interior wall assemblies, the additional times assigned in Clause B.8.1 of CSA O86, “Engineering design in
wood”, shall only be applied to the calculated fire-resistance rating where both sides of the assembly are protected in
accordance with Clause B.8 of CSA O86. Where the level of protection differs on the two sides, the additional time
corresponding to the lesser level of protection shall be applied.
(6) For exterior wall assemblies, the additional times assigned in Clause B.8.1 of CSA O86, “Engineering design in
Wood”, shall only be applied to the calculated fire-resistance rating where
(a) the interior (fire-exposed) side of the assembly is protected in accordance with Clause B.8 of CSA O86, and
(b) except where the assembly is constructed of cross-laminated timber panels with lapped or splined joints as described
in Sentence (4), the exterior (unexposed) side of the assembly is protected in accordance with Clause (3)(d).
2024MMAH Supplementary Standard SB-2
Section 3 Flame-Spread Ratings and Smoke Developed
Classifications
3.1.1.Scope of Information
(1) Tables 3.1.1.A. and 3.1.1.B. show flame-spread ratings and smoke developed classifications for combinations of
some common interior finish materials. The values are based on all the evidence available at present. Many materials
have not been included because of lack of test evidence or because of inability to classify or describe the material in
generic terms for the purpose of assigning ratings.
Table 3.1.1.A.
Assigned Flame-Spread Ratings and Smoke Developed Classifications
for Combinations of Wall and Ceiling Finish Materials and Surface Coatings (1)
Surface Coating
Paint or Varnish not more
Applicable Material Minimum than 1.3 mm Thick
Materials
Standard Thickness, mm Unfinished
Cellulosic Wallpaper not
more than One Layer(2)(3)
Brick, concrete, tile None None
Steel, copper, aluminum None 0.33 0/0 25/50
Gypsum plaster CSA A82.22-M None
CAN/CSA-A82.27-M
Gypsum board 9.5 25/50 25/50
ASTM C1396 / C1396M
Lumber None 16 150/300 150/300
Douglas Fir plywood(4) CSA O121
Poplar plywood(4) CSA O153 11 150/100 150/300
Plywood with Spruce face
CSA O151
veneer(4)
Douglas Fir plywood(4) CSA O121 6 150/100 150/100
Fiberboard low density CAN/ULC-S706 11 X/100 150/100
Particleboard ANSI A208.1 12.7 150/300 (5)
CSA O325 — (5) (5)
Waferboard, OSB
CSA O437.0 — (5) (5)
Column 1 2 3 4 5
Notes to Table 3.1.1.A.:
(1) See Sentence 1.1.1.(5) for standards used to assign flame-spread ratings and smoke developed classifications.
(2) Flame-spread ratings and smoke developed classifications for paints and varnish are not applicable to shellac and lacquer.
(3) Flame-spread ratings and smoke developed classifications for paints apply only to alkyd and latex paints.
(4) The flame-spread ratings and smoke developed classifications shown are for those plywoods without a cellulose resin overlay.
(5) Insufficient test information available.
Page 44 • SB-2
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-2
Table 3.1.1.B.
Flame-Spread Ratings and Smoke Developed Classifications
for Combinations of Common Floor Finish Materials and Surface Coatings(1)
Materials Applicable Standard FSR/SDC(2)
Hardwood or softwood flooring either unfinished or finished with a spar or urethane varnish
None 300/300
coating
Wool carpet (woven), pile weight not less than 1120 g/m2, applied with or without felt underlay(3) CAN/CGSB-4.129 300/300
Nylon carpet, pile weight not less than 610 g/m2 and not more than 800 g/m2, applied with or
CAN/CGSB-4.129 300/500
without felt underlay(3)
Nylon carpet, pile weight not less than 610 g/m2 and not more than 1355 g/m2, glued down to
CAN/CGSB-4.129 300/500
concrete
Wool/nylon blend carpet (woven) with not more than 20% nylon and pile weight not less than
CAN/CGSB-4.129 300/500
1120 g/m2
Nylon/wool blend carpet (woven) with not more than 50% wool, pile weight not less than 610 g/m2
CAN/CGSB-4.129 300/500
and not more than 800 g/m2
Polypropylene carpet, pile weight not less than 500 g/m2 and not more than 1200 g/m2, glued
CAN/CGSB-4.129 300/500
down to concrete
Column 1 2 3
Notes to Table 3.1.1.B.:
(1) Tested on the floor of the tunnel in conformance with provisions of CAN/ULC-S102.2, "Standard Method of Test for Surface Burning
Characteristics of Flooring, Floor Coverings, and Miscellaneous Materials and Assemblies".
(2) Flame-Spread Rating/Smoke Developed Classification
(3) Type 1 or 2 underlay as described in CGSB 4-GP-36M, "Carpet Underlay, Fiber Type".
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
3.1.2.Ratings
(1) The ratings shown in Tables 3.1.1.A. and 3.1.1.B. are arranged in groups corresponding to the provisions of this
Code. The ratings apply to materials falling within the general categories indicated.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
3.1.3.Table Entries
(1) In Tables 3.1.1.A. and 3.1.1.B., the first number of each entry relates to flame spread and the second number to
smoke developed limit. For example:
25/50 represents a flame-spread rating of 0 to 25 and a smoke developed classification of 0 to 50.
150/300 represents a flame-spread rating of 75 to 150 and a smoke developed classification of 100 to 300.
X/X applied to walls and ceilings means a flame-spread rating over 150 and a smoke developed classification over 300.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
3.1.4.Effect of Surface Coatings
(1) Thin surface coatings can modify flame-spread characteristics either upward or downward. Table 3.1.1.A. includes
a number of thin coatings that increase the flame-spread rating of the base material, so that these may be considered
where more precise control over flame spread hazard is desired.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
3.1.5.Proprietary Materials
(1) Information on flame-spread rating of proprietary materials and fire-retardant treatments that cannot be described in
sufficient detail to ensure reproducibility is available through the listing and labelling services of Underwriters'
Laboratories of Canada, Intertek Testing Services NA Ltd. or other recognized testing laboratory.
(2) A summary of flame-spread test results published prior to 1965 has been prepared by NRC (see Item (1) in
Subsection 7.1.).
3.1.6.Limitations and Conditions
(1) The propagation of flame along a surface in the standard test involves some finite depth of the material or materials
behind the surface, and this involvement extends to the depth to which temperature variations are to be found during the
course of the test; for many commonly used lining materials, such as wood, the depth involved is about 25 mm.
(2) For all the combustible materials described in Table 3.1.1.A., a minimum dimension is shown, and this represents
the thickness of the test samples on which the rating has been based; when used in greater thicknesses than that shown,
these materials may have a slightly lower flame-spread rating, and thinner specimens may have higher flame-spread
ratings.
(3) No rating has been included for foamed plastic materials because it is not possible at this time to identify these
products with sufficient accuracy on a generic basis. Materials of this type which melt when exposed to the test flame
generally show an increase in flame-spread rating as the thickness of the test specimen increases.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
3.1.7.Referenced Standards
In Tables 3.1.1.A. and 3.1.1.B., the standards applicable to the materials described are noted because the ratings depend on
conformance with these specifications.
Section 4 Noncombustibility
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
4.1.1.Determination of Noncombustibility
(1) Noncombustibility is required of certain components of buildings by the provisions of this Code, which specifies
noncombustibility by reference to CAN/ULC-S114, "Standard Method of Test for Determination of Non-Combustibility
in Building Materials".
(2) The test to which reference is made in Sentence (1) is severe, and it may be assumed that any building material
containing even a small proportion of combustibles will itself be classified as combustible. The specimen, 38 mm by
51 mm, is exposed to a temperature of 750°C in a small furnace. The essential criteria for noncombustibility are that the
specimen does not flame or contribute to temperature rise.
4.2.1.Combustible Materials
(1) Most materials from animal or vegetable sources will be classed as combustible by CAN/ULC-S114, "Standard
Method of Test for Determination of Non-Combustibility in Building Materials", and wood, wood fibreboard, paper, felt
made from animal or vegetable fibres, cork, plastics, asphalt and pitch would therefore be classed as combustible.
Page 46 • SB-2
4.2.2.Composite Materials
(1) Materials that consist of combustible and noncombustible elements in combination will in many cases also be
classed as combustible, unless the proportion of combustibles is very small. Some mineral wool insulations with
combustible binder, cinder concrete, cement and wood chips and wood-fibred gypsum plaster would also be classed as
combustible.
4.2.3.Effect of Chemical Additives
(1) The addition of a fire-retardant chemical is not sufficient to change a combustible product to a noncombustible
product.
4.3.1.Typical Examples
(1) Noncombustible materials include brick, ceramic tile, concrete made from Portland cement with noncombustible
aggregate, plaster made from gypsum with noncombustible aggregate, metals commonly used in buildings, glass, granite,
sandstone, slate, limestone and marble.
Section 5 Protection of Openings in Fire-Rated
Assemblies
5.1.1.Installation Information
(1) The information in this Section specifies requirements for the installation of fire doors and fire dampers in gypsum-
board-protected stud wall assemblies.
5.2.1.References
(1) Fire doors and fire dampers in gypsum-board-protected steel stud non-loadbearing walls required to have a fire-
resistance rating shall be installed in conformance with Section 9.24. of Division B of the Building Code and the
applicable requirements of NFPA 80, "Fire Doors and Other Opening Protectives".
(2) Fire doors and fire dampers in gypsum-board-protected wood stud walls required to have a fire-resistance rating
shall be installed in conformance with Section 9.23. of Division B of the Building Code and the applicable requirements
of NFPA 80, "Fire Doors and Other Opening Protectives".
2024MMAH Supplementary Standard SB-2
Section 6 Fire Performance of Exterior Wall Assemblies
6.1.1.Exterior Wall Assemblies
(1) Table 6.1.1. shows construction specifications for exterior wall assemblies that are deemed to satisfy the criteria of
Clause 3.1.5.5.(1)(b) when tested in accordance with CAN/ULC-S134, “Standard Method of Fire Test of Exterior Wall
Assemblies”.
Table D-6.1.1.
Construction Specifications for Exterior Wall Assemblies that are Deemed to Satisfy the Criteria of Clause 3.1.5.5.(1)(b)
when Tested in Accordance with CAN/ULC-S134
Wall
Structural Members Absorptive Material Sheathing Cladding Design
Number
38 mm × 89 mm 89 mm thick rock or 12.7 mm thick
EXTW-1 wood studs spaced slag fibre in cavities — fire-retardant-treated
at 400 mm o.c.(1)(2) formed by studs(3)(4) plywood siding(5)
38 mm × 140 mm 140 mm thick rock or
EXTW-2 wood studs spaced slag fibre in cavities Gypsum sheathing Noncombustible
≥ 12.7 mm thick exterior cladding
at 400 mm o.c.(1)(2) formed by studs(3)(4)
38 mm × 140 mm 140 mm thick rock or 15.9 mm thick
Noncombustible
EXTW-3 wood studs spaced slag fibre in cavities fire-retardant-
exterior cladding
at 400 mm o.c.(1)(2) formed by studs(3)(4) treated plywood(6)
38 mm × 140 mm
wood studs spaced
140 mm thick glass,
at 600 mm o.c.(1)(7) rock or slag fibre in Gypsum sheathing Noncombustible
EXTW-4 attached to cross- cavities formed by ≥ 12.7 mm thick exterior cladding
laminated timber
(CLT) wall panels ≥ studs(3)
38 mm thick(8)
89 mm horizontal Z- Noncombustible
bars spaced at exterior cladding
89 mm thick rock or
600 mm o.c. attached to 19 mm
EXTW-5 attached to CLT wall slag fibre in cavities —
vertical hat channels
panels ≥ 105 mm formed by Z-bars(3)(4) spaced at 600 mm
thick(8) o.c.
Col. 1 2 3 4 5 6
Page 48 • SB-2
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2024MMAH Supplementary Standard SB-2
Notes to Table 6.1.1.:
(1) The stated stud dimensions are maximum values. Where wood studs with a smaller depth are used, the thickness of the absorptive
material in the cavities formed by the studs must be reduced accordingly.
(2) Horizontal blocking between the vertical studs or horizontal stud plates must be installed at vertical intervals of not more than
2 324 mm, such that the maximum clear length between the horizontal blocking or stud plates is 2 286 mm.
(3) The absorptive material must conform to CAN/ULC-S702.1, “Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1:
Material Specification”.
(4) The absorptive material must have a density not less than 32 kg/m 3.
(5) The fire-retardant-treated plywood siding must conform to the requirements of Article 3.1.4.5. and must have been conditioned in
conformance with ASTM D2898, “Standard Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing”,
before being tested in accordance with CAN/ULC-S102, “Standard Method of Test for Surface Burning Characteristics of Building
Materials and Assemblies”.
(6) The fire-retardant-treated plywood must conform to the requirements of Article 3.1.4.5.
(7) Horizontal blocking between the vertical studs or horizontal stud plates must be installed at vertical intervals of not more than
2 438 mm, such that the maximum clear length between the horizontal blocking or stud plates is 2 400 mm.
(8) A water-resistant barrier is permitted to be attached to the face of the CLT wall panels.
Section 7 Background Information
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
7.1.Fire Test Reports
Summaries of available fire test information have been published by NRC as follows:
(1) M. Galbreath, Flame Spread Performance of Common Building Materials. Technical Paper No. 170, Division of
Building Research, National Research Council Canada, Ottawa, April 1964. NRCC 7820.
(2) M. Galbreath and W.W. Stanzak, Fire Endurance of Protected Steel Columns and Beams. Technical Paper No. 194,
Division of Building Research, National Research Council Canada, Ottawa, April 1965. NRCC 8379.
(3) T.Z. Harmathy and W.W. Stanzak, Elevated-Temperature Tensile and Creep Properties of Some Structural and
Prestressing Steels. American Society for Testing and Materials, Special Technical Publication 464, 1970, p. 186
(DBR Research Paper No. 424) NRCC 11163.
(4) T.Z. Harmathy, Thermal Performance of Concrete Masonry Walls in Fire. American Society for Testing and
Materials, Special Technical Publication 464, 1970, p. 209 (DBR Research Paper No. 423) NRCC 11161.
(5) L.W. Allen, Fire Endurance of Selected Non-Loadbearing Concrete Masonry Walls. DBR Fire Study No. 25,
Division of Building Research, National Research Council Canada, Ottawa, March 1970. NRCC 11275.
(6) A. Rose, Comparison of Flame Spread Ratings by Radiant Panel, Tunnel Furnace, and Pittsburgh-Corning
Apparatus. DBR Fire Study No. 22, Division of Building Research, National Research Council Canada, Ottawa,
June 1969. NRCC 10788.
(7) T.T. Lie and D.E. Allen, Calculation of the Fire Resistance of Reinforced Concrete Columns. DBR Technical Paper
No. 378, Division of Building Research, National Research Council Canada, Ottawa, August 1972. NRCC 12797.
(8) W.W. Stanzak, Column Covers: A Practical Application of Sheet Steel as a Protective Membrane. DBR Fire Study
No. 27, Division of Building Research, National Research Council Canada, Ottawa, February 1972. NRCC 12483.
(9) W.W. Stanzak, Sheet Steel as a Protective Membrane for Steel Beams and Columns. DBR Fire Study No. 23,
Division of Building Research, National Research Council Canada, Ottawa, November 1969. NRCC 10865.
(10) W.W. Stanzak and T.T. Lie, Fire Tests on Protected Steel Columns with Different Cross-Sections. DBR Fire Study
No. 30, Division of Building Research, National Research Council Canada, Ottawa, February 1973. NRCC 13072.
2024MMAH Supplementary Standard SB-2
(11) G. Williams-Leir and L.W. Allen, Prediction of Fire Endurance of Concrete Masonry Walls. DBR Technical Paper
No. 399, Division of Building Research, National Research Council Canada, Ottawa, November 1973. NRCC
13560.
(12) G. Williams-Leir, Prediction of Fire Endurance of Concrete Slabs. DBR Technical Paper No. 398, Division of
Building Research, National Research Council Canada, Ottawa, November 1973. NRCC 13559.
(13) A. Rose, Flammability of Fibreboard Interior Finish Materials. Building Research Note No. 68, Division of
Building Research, National Research Council Canada, Ottawa, October 1969.
(14) L.W. Allen, Effect of Sand Replacement on the Fire Endurance of Lightweight Aggregate Masonry Units. DBR
Fire Study No. 26, Division of Building Research, National Research Council Canada, Ottawa, September 1971.
NRCC 12112.
(15) L.W. Allen, W.W. Stanzak and M. Galbreath, Fire Endurance Tests on Unit Masonry Walls with Gypsum Board.
DBR Fire Study No. 32, Division of Building Research, National Research Council Canada, Ottawa, February 1974,
NRCC 13901.
(16) W.W. Stanzak and T.T. Lie, Fire Resistance of Unprotected Steel Columns. Journal of Structural Division, Proc.,
Am. Soc. Civ. Eng., Vol. 99, No. ST5 Proc. Paper 9719, May 1973 (DBR Research Paper No. 577) NRCC 13589.
(17) T.T. Lie and T.Z. Harmathy, Fire Endurance of Concrete-Protected Steel Columns. A.C.I. Journal, January 1974,
Title No. 71-4 (DBR Technical Paper No. 597) NRCC 13876.
(18) T.T. Lie, A Method for Assessing the Fire Resistance of Laminated Timber Beams and Columns. Can. J. Civ. Eng.,
Vol. 4, No. 2, June 1977 (DBR Technical Paper No. 718) NRCC 15946.
(19) T.T. Lie, Calculation of the Fire Resistance of Composite Concrete Floor and Roof Slabs. Fire Technology, Vol. 14,
No. 1, February 1978 (DBR Technical Paper No. 772) NRCC 16658.
(20) M.A. Sultan, Y.P Séguin and P. Leroux. Results of Fire Resistance Tests on Full-Scale Floor Assemblies, Institute
for Research in Construction, National Research Council of Canada, Ottawa, May 1998, IRC-IR-764.
(21) M.A. Sultan, J.C. Latour, P. Leroux, R.C. Monette, Y.P Séguin and J.P. Henrie, Results of Fire Resistance Tests on
Full-Scale Floor Assemblies – Phase II, Institute for Research in Construction, National Research Council of
Canada, Ottawa, March 2005, RR-184.
(22) M.A. Sultan and G.D. Lougheed, Results of Fire Resistance Tests on Full-Scale Gypsum Board Wall Assemblies,
Institute for Research in Construction, National Research Council of Canada, Ottawa, August 2002, IRC-IR-833.
(23) V.K.R. Kodur, M.A. Sultan, J.C. Latour, P. Leroux, R.C. Monette, Experimental Studies on the Fire Resistance of
Load-Bearing Steel Stud Walls, Research Report, National Research Council of Canada, Ottawa, August 2013, RR-
343.
(24) E. Gibbs, B.C. Taber, G.D. Lougheed, J.Z. Su and N. Bénichou, Solutions for Mid-Rise Wood Construction: Full-
Scale Standard Fire Test for Exterior Wall Assembly Using Lightweight Wood Frame Construction with Gypsum
Sheathing (Test EXTW-1), Report to Research Consortium for Wood and Wood-Hybrid Mid-Rise Buildings,
National Research Council Canada, Ottawa, December 2014, A1-100035-01.4.
(25) E. Gibbs, B.C. Taber, G.D. Lougheed, J.Z. Su and N. Bénichou, Solutions for Mid-Rise Wood Construction: Full-
Scale Standard Fire Test for Exterior Wall Assembly Using a Simulated Cross-Laminated Timber Wall Assembly
with Gypsum Sheathing (Test EXTW-2), Report to Research Consortium for Wood and Wood-Hybrid Mid-Rise
Buildings, National Research Council Canada, Ottawa, December 2014, A1-100035-01.5.
(26) E. Gibbs, B.C. Taber, G.D. Lougheed, J.Z. Su and N. Bénichou, Solutions for Mid-Rise Wood Construction: Full-
Scale Standard Fire Test for Exterior Wall Assembly Using Lightweight Wood Frame Construction with Interior
Fire-Retardant-Treated Plywood Sheathing (Test EXTW-3), Report to Research Consortium for Wood and Wood-
Hybrid Mid-Rise Buildings, National Research Council Canada, Ottawa, December 2014, A1-100035-01.6.
(27) E. Gibbs and J. Su, Full Scale Exterior Wall Test on Nordic Cross-Laminated Timber System, National Research
Council Canada, Ottawa, January 2015, A1-006009.1.
Page 50 • SB-2
7.2.Obsolete Materials and Assemblies
Building materials, components and structural members and assemblies in buildings constructed before 1995 may have
been assigned ratings based on earlier editions of The Supplement to the National Building Code of Canada or older reports
of fire tests. To assist users in determining the ratings of these obsolete assemblies and structural members, the following
list of reference documents has been prepared. Although some of these publications are out of print, reference copies are
available through NRC.
(1) M. Galbreath, Fire Endurance of Unit Masonry Walls. Technical Paper No. 207, Division of Building Research,
National Research Council Canada, Ottawa, October 1965. NRCC 8740.
(2) M. Galbreath, Fire Endurance of Light Framed and Miscellaneous Assemblies. Technical Paper No. 222, Division
of Building Research, National Research Council Canada, Ottawa, June 1966. NRCC 9085.
(3) M. Galbreath, Fire Endurance of Concrete Assemblies. Technical Paper No. 235, Division of Building Research,
National Research Council Canada, Ottawa, November 1966. NRCC 9279.
(4) Guideline on Fire Ratings of Archaic Materials and Assemblies. Rehabilitation Guideline #8, U.S. Department of
Housing and Urban Development, Germantown, Maryland 20767, October 1980.
(5) T.Z. Harmathy, Fire Test of a Plank Wall Construction. Fire Study No. 2, Division of Building Research, National
Research Council Canada, Ottawa, July 1960. NRCC 5760.
(6) T.Z. Harmathy, Fire Test of a Wood Partition. Fire Study No. 3, Division of Building Research, National Research
Council Canada, Ottawa, October 1960. NRCC 5769.
7.3.Assessment of Archaic Assemblies
Information in this document applies to new construction. Please refer to early editions of the Supplement to the National
Building Code of Canada for the assessment or evaluation of assemblies that do not conform to the information in this
edition of the Building Code. As with other documents, this Code is revised according to the information presented to the
standing committee responsible for its content, and with each update new material may be added and material that is not
relevant may be deleted.
7.4.Development of the Component Additive Method
The component additive method was developed based upon the following observations and conclusions drawn from
published as well as unpublished test information.
Study of the test data showed that structural failure preceded failure by other criteria (transmission of heat or hot gases) in
most of the tests of loadbearing wood-framed assemblies. The major contributor to fire resistance was the membrane on
the fire-exposed side.
Fire tests of wood joist floors without protective ceilings resulted in structural failure between 8 and 10 min. Calculation of
the time for wood joists to approach breaking stress, based upon the charring rate of natural woods, suggested a time of
10 min for structural failure. This time was subtracted from the fire-resistance test results of wood joist floors and the
remainder considered to be the contribution of the membrane.
The figures obtained for the contribution of membranes were then applied to the test results for open web steel joist floors
and wood and steel stud walls and values of 20 min for the contribution of wood stud framing and 10 min for steel framing
were derived.
2024MMAH Supplementary Standard SB-2
The fire-resistance rating has been limited to 1.5 h as this method of developing ratings for framed assemblies was new and
untried. Although this is the subject of current review, no decision has been made to extend the ratings beyond 1.5 h.
(1) M. Galbreath, G. C. Gosselin, and R. B. Chauhan, Historical Guide to Chapter 2 of the Supplement to the National
Building Code of Canada, Committee Paper FPR 1-3, Prepared for the Standing Committee on Fire Performance
Ratings, May 1987.
Example showing fire-resistance rating of a typical membrane assembly, calculated using the component additive method.
1Hour Gypsum Board/Wood Stud Interior Partition
A 1 h fire-resistance rating is required for an interior wood framed partition, using 12.7 mm Type X gypsum board.
(a) Since gypsum board is used (Sentence 2.3.4.(2) and Table 2.3.4.A.) time assigned to 12.7 mm Type X gypsum
board membrane on the fire-exposed side of the partition = 25 min
(b) Time assigned to wood framing members at 406 mm o.c. (Sentence 2.3.4.(3) and Table 2.3.4.E.) = 20 min
(c) Time assigned to insulation, if the spaces between the studs are filled with preformed insulation of rock or slag
fibres conforming to CAN/ULC-S702.1, "Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1:
Material Specification ", (Sentence 2.3.4.(4) and Table 2.3.4.G.) = 15 min
(d) Time assigned to the membrane on the non-fire-exposed side (Sentence 2.3.5.(1)) = 0 min
Fire-resistance rating = 25 + 20 + 15 = 60 min
Page 52 • SB-2
Ministry of Municipal Affairs and Housing
Building and Development Branch
MMAH Supplementary Standard SB-3
MMAH Supplementary Standard SB-3
Fire and Sound Resistance Tables
January 1, 2024
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
2024MMAH Supplementary Standard SB-3
COMMENCEMENT
MMAH Supplementary Standard SB-3 comes into force on the 1st day of January 2025.
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