PART 3 — FIRE PROTECTION, OCCUPANT SAFETY AND ACCESSIBILITYUpdated for the 2024 Ontario Building Code
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3.2.3.1.Limiting Distance and Area of Unprotected Openings
(1) Except as permitted by Articles 3.2.3.10. to 3.2.3.12., the area of unprotected openings in an exposing building face
for the applicable limiting distance shall be not more than the value determined in accordance with
(a) Table 3.2.3.1.-B or Table 3.2.3.1.-C for an exposing building face conforming to Article 3.2.3.2. of a building or fire
compartment which is not sprinklered, or
(b) Table 3.2.3.1.-D or Table 3.2.3.1.-E for an exposing building face conforming to Article 3.2.3.2. of a sprinklered fire
compartment that is part of a building which is sprinklered in conformance with Section 3.2.
(See Note A-3)
(See also Article 3.1.18.3.)
(2) The area of the unprotected openings in an exposing building face shall be the aggregate area of unprotected
openings expressed as a percentage of the area of the exposing building face in Table 3.2.3.1.-B, 3.2.3.1.-C, 3.2.3.1.-D or
3.2.3.1.-E. (See Sentence 3.2.3.2.(1))
(3) For the purpose of determining the type of construction and cladding and the fire-resistance rating of an exterior
wall,
(a) the exposing building face shall be taken as the projection of the exterior wall onto a vertical plane located so that no
portion of the exterior wall of the building or of a fire compartment, if the fire compartment complies with the
requirements of Article 3.2.3.2., is between the vertical plane and the line to which the limiting distance is measured,
and
(b) the area of unprotected openings shall be determined from Table 3.2.3.1.-B, 3.2.3.1.-C, 3.2.3.1.-D or 3.2.3.1.-E.
(4) For the purpose of determining the actual percentage of unprotected openings permitted in an exterior wall, the
location of the exposing building face is permitted to be taken at a vertical plane located so that there are no unprotected
openings between the vertical plane and the line to which the limiting distance is measured. (See Note A-3.2.3.1.(4))
(5) Except for buildings that are sprinklered, where the limiting distance is 2 m or less, individual unprotected openings
in an exposing building face shall be no greater than
(a) the area stated in Table 3.2.3.1.-A, or
(b) where the limiting distance equal to or greater than 1.2 m, the area calculated by
Area = 0.24 [(2 x LD) - 1.2]2
where
Area = area of the unprotected opening, and
LD = limiting distance.
86b Division B – Part 3
Table 3.2.3.1.-A
Maximum Concentrated Area of Unprotected Openings
Forming Part of Sentence 3.2.3.1.(5)
Maximum Area of Individual
Limiting Distance, m
Unprotected Openings, m2
1.2 0.35
1.5 0.78
2.0 1.88
(6) The spacing between individual unprotected openings described in Sentence (5) that serve a single room or space
described in Sentence (7) shall not be less than
(a) 2 m horizontally of another unprotected opening that is on the same exposing building face and serves the single
room or space, or
(b) 2 m vertically of another unprotected opening that serves the single room or space, or another room or space on the
same storey.
(7) For the purpose of Sentence (6), “single room or space” means a room or space that
(a) is not divided by a wall,
(b) is divided by
(i) a wall that extends less than 1.5 m from the interior face of the exterior wall, or
(ii) a partial height wall, or
(c) consists of two or more stacked spaces that are on the same storey.
(8) If a building has any storey that is not sprinklered and firefighting facilities cannot reach it within 10 min of the
alarm being received, the required limiting distance shall be doubled.
(9) If the surface temperature on the unexposed surface of a wall assembly exceeds the temperature limit of a standard
fire test as permitted by Article 3.1.7.2., an allowance shall be made for the radiation from the hot unexposed wall surface
by adding an equivalent area of unprotected opening to the area of actual openings as follows:
AC = A + (AF × FEO)
where
AC = corrected area of unprotected openings including actual and equivalent openings,
A = actual area of unprotected openings,
AF = area of exterior surface of the exposing building face, exclusive of openings, on which the temperature
limit of the standard test is exceeded, and
FEO = an equivalent opening factor derived from the following expression:
(Tu + 273 ) 4
FEO =
(Te + 273 ) 4
Tu = average temperature in degrees Celsius of the unexposed wall surface at the time the required fire-
resistance rating is reached under test conditions,
Te = 892°C for a fire-resistance rating not less than 45 min, 927°C for a fire-resistance rating not less than
1 h, and 1 010°C for a fire-resistance rating not less than 2 h.
(10) Unless a closure used to protect an opening in an exposing building face has a protective performance equivalent to
that required for the wall assembly in which it is located, an equivalent area of unprotected opening, determined in
accordance with the procedures of Sentence (9) shall be added to the greater of
(a) the actual area of unprotected openings, or
(b) the corrected area of unprotected openings.
(11) The required limiting distance for an exposing building face is permitted to be measured to a point beyond the
property line that is not the centre line of a street, lane or public thoroughfare if
(a) the owners of the properties on which the limiting distance is measured and the municipality enter into an agreement
in which such owners agree that,
(i) each owner covenants that, for the benefit of land owned by the other covenantors, the owner will not
construct a building on his or her property unless the limiting distance for exposing building faces in respect
of the proposed construction is measured in accordance with the agreement,
(ii) the covenants contained in the agreement are intended to run with the lands, and the agreement shall be
binding on the parties and their respective heirs, executors, administrators, successors and assigns,
(iii) the agreement shall not be amended or deleted from title without the consent of the municipality, and
(iv) they will comply with such other conditions as the municipality considers necessary, including
indemnification of the municipality by the other parties, and
(b) the agreement referred to in Clause (a) is registered against the title of the properties to which it applies.
(12) Where an agreement referred to in Sentence (11) is registered against the title of a property, the limiting distance for
exposing building faces shall be measured to the point referred to in the agreement.
Table 3.2.3.1.-B
Unprotected Opening Limits for a Building or Fire Compartment that is not Sprinklered Throughout
Forming Part of Article 3.2.3.1.
Exposing Building Face Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, %
Maximum Area, Ratio Limiting Distance, m
m2 (L/H or H/L)(1) 0 1.2 1.5 2 2.5 3 4 5 6 7 8 9 10 11 12 13 14 16 18 20 25 30 35 40 45 50
Less than 3:1 0 8 10 18 29 46 91 100
10 3:1 to 10:1 0 8 12 21 33 50 96 100
over 10:1 0 11 18 32 48 68 100
Less than 3:1 0 7 9 14 22 33 63 100
15 3:1 to 10:1 0 8 10 17 25 37 67 100
over 10:1 0 10 15 26 39 53 87 100
Less than 3:1 0 7 9 12 18 26 49 81 100
20 3:1 to 10:1 0 8 10 15 21 30 53 85 100
over 10:1 0 9 14 23 33 45 72 100
Less than 3:1 0 7 8 11 16 23 41 66 98 100
25 3:1 to 10:1 0 8 9 13 19 26 45 70 100
over 10:1 0 9 13 21 30 39 62 90 100
Less than 3:1 0 7 8 11 15 20 35 56 83 100
30 3:1 to 10:1 0 7 9 12 17 23 39 61 88 100
over 10:1 0 8 12 19 27 36 56 79 100
Less than 3:1 0 7 8 10 13 17 28 44 64 89 100
40 3:1 to 10:1 0 7 8 11 15 20 32 48 69 93 100
over 10:1 0 8 11 17 24 31 47 66 88 100
Less than 3:1 0 7 8 9 12 15 24 37 53 72 96 100
50 3:1 to 10:1 0 7 8 10 14 18 28 41 57 77 100
over 10:1 0 8 10 15 21 28 41 57 76 97 100
Less than 3:1 0 7 8 9 11 14 21 32 45 62 81 100
60 3:1 to 10:1 0 7 8 10 13 16 25 36 49 66 85 100
over 10:1 0 8 10 14 20 25 38 51 67 85 100
Less than 3:1 0 7 7 8 10 12 18 26 36 48 62 79 98 100
80 3:1 to 10:1 0 7 8 9 11 14 21 29 40 52 67 84 100
over 10:1 0 8 9 13 17 22 32 44 56 70 86 100
Less than 3:1 0 7 7 8 9 11 16 22 30 40 51 65 80 97 100
100 3:1 to 10:1 0 7 8 9 11 13 18 25 34 44 56 69 84 100
over 10:1 0 7 9 12 16 20 29 39 49 61 74 89 100
Less than 3:1 0 7 7 8 9 10 13 17 22 29 37 46 56 67 79 93 100
150 3:1 to 10:1 0 7 7 8 10 11 15 20 26 33 41 50 60 71 84 97 100
over 10:1 0 7 8 11 13 17 24 31 39 48 57 68 79 91 100
Less than 3:1 0 7 7 7 8 9 10 13 16 20 25 30 36 43 51 59 68 87 100
250 3:1 to 10:1 0 7 7 8 9 10 12 15 19 24 28 34 40 47 55 63 72 92 100
over 10:1 0 7 8 9 11 14 19 24 30 36 43 50 57 65 73 82 92 100
Less than 3:1 0 7 7 7 8 8 9 11 14 16 20 24 28 33 38 44 50 64 81 99 100
350 3:1 to 10:1 0 7 7 8 9 9 11 13 16 19 23 27 32 37 42 48 55 69 85 100
over 10:1 0 7 8 9 10 12 16 21 25 30 36 41 47 53 59 66 73 88 100
Less than 3:1 0 7 7 7 7 8 9 10 12 14 16 19 22 25 29 33 37 47 59 71 100
500 3:1 to 10:1 0 7 7 7 8 8 10 12 14 16 19 22 25 29 33 37 41 52 63 76 100
over 10:1 0 7 7 8 9 11 14 18 22 25 30 34 38 43 48 53 58 70 82 96 100
Less than 3:1 0 7 7 7 7 7 8 9 9 10 12 13 14 16 18 20 22 27 33 39 58 82 100
1 000 3:1 to 10:1 0 7 7 7 7 8 9 10 11 12 14 15 17 19 21 23 26 31 37 43 63 86 100
over 10:1 0 7 7 8 8 9 11 13 16 19 21 24 27 30 33 36 39 46 53 60 82 100
Less than 3:1 0 7 7 7 7 7 7 8 8 9 9 10 11 12 13 14 15 17 20 23 33 44 58 74 93 100
2 000 3:1 to 10:1 0 7 7 7 7 7 8 8 9 10 11 12 13 14 15 16 17 20 23 27 37 49 63 79 97 100
over 10:1 0 7 7 7 8 8 9 11 12 14 16 18 19 21 23 25 27 32 36 40 53 66 82 99 100
Notes to Table 3.2.3.1.-B:
(1) Apply whichever is greater,
L = Length of exposing building face
H = Height of exposing building face
Table 3.2.3.1.-C
Unprotected Opening Limits for a Building or Fire Compartment that is not Sprinklered Throughout
Forming Part of Article 3.2.3.1.
Exposing Building Face Area of Unprotected Openings for Groups E and F, Division 1 and 2 Occupancies, %
Maximum Ratio Limiting Distance, m
Area, m2 (L/H or H/L)(1) 0 1.2 1.5 2 2.5 3 4 5 6 7 8 9 10 11 12 13 14 16 18 20 25 30 35 40 45 50 55 60 65 70
Less than 3:1 0 4 5 9 15 23 46 77 100
10 3:1 to 10:1 0 4 6 10 17 25 48 79 100
over 10:1 0 5 9 16 24 34 58 91 100
Less than 3:1 0 4 5 7 11 16 32 53 79 100
15 3:1 to 10:1 0 4 5 8 13 18 34 55 82 100
over 10:1 0 5 8 13 19 26 43 66 93 100
Less than 3:1 0 4 4 6 9 13 25 40 61 85 100
20 3:1 to 10:1 0 4 5 7 11 15 27 43 63 87 100
over 10:1 0 5 7 11 17 22 36 53 74 99 100
Less than 3:1 0 4 4 6 8 11 20 33 49 69 92 100
25 3:1 to 10:1 0 4 5 7 9 13 22 35 51 71 94 100
over 10:1 0 4 6 10 15 20 31 45 62 82 100
Less than 3:1 0 4 4 5 7 10 18 28 42 58 77 100
30 3:1 to 10:1 0 4 4 6 9 12 20 30 44 60 80 100
over 10:1 0 4 6 10 14 18 28 40 54 71 91 100
Less than 3:1 0 4 4 5 6 8 14 22 32 44 59 76 94 100
40 3:1 to 10:1 0 4 4 6 8 10 16 24 34 47 61 78 97 100
over 10:1 0 4 5 8 12 15 23 33 44 57 72 89 100
Less than 3:1 0 4 4 5 6 7 12 18 26 36 48 61 76 93 100
50 3:1 to 10:1 0 4 4 5 7 9 14 20 29 38 50 63 79 95 100
over 10:1 0 4 5 8 11 14 21 29 38 48 61 74 90 100
Less than 3:1 0 4 4 4 5 7 11 16 23 31 40 52 64 78 94 100
60 3:1 to 10:1 0 4 4 5 6 8 12 18 25 33 43 54 66 81 96 100
over 10:1 0 4 5 7 10 13 19 26 34 43 53 64 77 92 100
Less than 3:1 0 4 4 4 5 6 9 13 18 24 31 40 49 60 71 84 98 100
80 3:1 to 10:1 0 4 4 5 6 7 10 15 20 26 33 42 51 62 74 86 100
over 10:1 0 4 5 6 9 11 16 22 28 35 43 52 62 73 85 98 100
Less than 3:1 0 4 4 4 5 5 8 11 15 20 26 32 40 48 58 68 79 100
100 3:1 to 10:1 0 4 4 4 5 6 9 13 17 22 28 35 42 51 60 70 81 100
over 10:1 0 4 4 6 8 10 14 19 25 31 37 44 52 61 71 81 92 100
Less than 3:1 0 4 4 4 4 5 6 8 11 14 18 23 28 33 40 46 54 70 89 100
150 3:1 to 10:1 0 4 4 4 5 6 8 10 13 16 20 25 30 36 42 49 56 73 92 100
over 10:1 0 4 4 5 7 8 12 16 20 24 29 34 39 46 52 59 67 84 100
Less than 3:1 0 4 4 4 4 4 5 7 8 10 12 15 18 22 25 29 34 44 55 68 100
250 3:1 to 10:1 0 4 4 4 4 5 6 8 10 12 14 17 20 24 27 32 36 46 57 70 100
over 10:1 0 4 4 5 6 7 9 12 15 18 21 25 28 32 37 41 46 56 68 81 100
Less than 3:1 0 4 4 4 4 4 5 6 7 8 10 12 14 16 19 22 25 32 40 49 77 100
350 3:1 to 10:1 0 4 4 4 4 4 5 7 8 10 12 14 16 18 21 24 27 34 43 52 79 100
over 10:1 0 4 4 4 5 6 8 10 13 15 18 21 23 26 30 33 36 44 53 62 90 100
Less than 3:1 0 4 4 4 4 4 4 5 6 7 8 9 11 13 14 16 19 24 29 36 55 78 100
500 3:1 to 10:1 0 4 4 4 4 4 5 6 7 8 9 11 13 14 16 18 21 26 31 38 57 80 100
over 10:1 0 4 4 4 5 5 7 9 11 13 15 17 19 21 24 26 29 35 41 48 68 92 100
Less than 3:1 0 4 4 4 4 4 4 4 5 5 6 6 7 8 9 10 11 14 16 20 29 41 55 71 89 100
1 000 3:1 to 10:1 0 4 4 4 4 4 4 5 5 6 7 8 9 10 11 12 13 15 18 22 31 43 57 73 91 100
over 10:1 0 4 4 4 4 5 6 7 8 9 11 12 13 15 16 18 20 23 26 30 41 53 68 84 100
Less than 3:1 0 4 4 4 4 4 4 4 4 4 5 5 5 6 6 7 7 9 10 12 16 22 29 37 46 56 68 80 94 100
2 000 3:1 to 10:1 0 4 4 4 4 4 4 4 5 5 5 6 6 7 7 8 9 10 12 13 18 24 31 39 49 59 70 83 96 100
over 10:1 0 4 4 4 4 4 5 5 6 7 8 9 10 11 12 13 14 16 18 20 26 33 41 50 59 70 81 94 100
Notes to Table 3.2.3.1.-C:
(1) Apply whichever is greater,
L = Length of exposing building face
H = Height of exposing building face
Table 3.2.3.1.-D
Unprotected Opening Limits for a Building or Fire Compartment that is Sprinklered Throughout
Forming Part of Sentence 3.1.6.9.(5) and Article 3.2.3.1.
Exposing Building Face Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, %
Limiting Distance, m
Maximum Area, m2
0 1.2 1.5 2 2.5 3 4 5 6 7 8 9
10 0 16 24 42 66 100
15 0 16 20 34 50 74 100
20 0 16 20 30 42 60 100
25 0 16 18 26 38 52 90 100
30 0 14 18 24 34 46 78 100
40 0 14 16 22 30 40 64 96 100
50 0 14 16 20 28 36 56 82 100
60 0 14 16 20 26 32 50 72 98 100
80 0 14 16 18 22 28 42 58 80 100
100 0 14 16 18 22 26 36 50 68 88 100
150 or more 0 14 14 16 20 22 30 40 52 66 82 100
Table 3.2.3.1.-E
Unprotected Opening Limits for a Building or Fire Compartment that is Sprinklered Throughout
Forming Part of Sentence 3.1.6.9.(5) and Article 3.2.3.1.
Exposing Building Face Area of Unprotected Opening for Groups E and F, Division 1 and 2 Occupancies, %
Limiting Distance, m
Maximum Area, m2
0 1.2 1.5 2 2.5 3 4 5 6 7 8 9 10 11 12 13 14 15
10 0 8 12 20 34 50 96 100
15 0 8 10 16 26 36 68 100
20 0 8 10 14 22 30 54 86 100
25 0 8 10 14 18 26 44 70 100
30 0 8 8 12 18 24 40 60 88 100
40 0 8 8 12 16 20 32 48 68 94 100
50 0 8 8 10 14 18 28 40 58 76 100
60 0 8 8 10 12 16 24 36 50 66 86 100
80 0 8 8 10 12 14 20 30 40 52 66 84 100
100 0 8 8 8 10 12 18 26 34 44 56 70 84 100
150 0 8 8 8 10 12 16 20 26 32 40 50 60 72 84 98 100
200 or more 0 8 8 8 8 10 14 18 22 28 34 42 50 60 68 80 92 100
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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