The Ontario Building Code | Limiting Distance and Area of Unprotected Openings

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 distanceshall 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 that 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 buildingthat is sprinklered in conformance with Section 3.2.

(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 facein Table 3.2.3.1.B., Table 3.2.3.1.C., Table 3.2.3.1.D. or Table 3.2.3.1.E.

(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., Table 3.2.3.1.C., Table 3.2.3.1.D. or Table 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.

(5) Except for buildings that are sprinklered, where the limiting distance is 2 m or less, the area of each individual unprotected opening in an exposing building face shall not be greater than,

(a) the area in Table 3.2.3.1.A., or

(b) for a limiting distance equal to or greater than 1.2 m, the area calculated as follows:

Area = 0.24 [(2 x LD) - 1.2]²

where,

Area = area of the unprotected opening in m², and

LD = limiting distance in m.

Table 3.2.3.1.A
Maximum Concentrated Area of Unprotected Openings

Forming Part of Sentence 3.2.3.1.(5)

Item	Column 1 Limiting Distance, m	Column 2 Maximum Area of Individual Unprotected Openings, m2
1.	1.2	0.35
2.	1.5	0.78
3.	2.0	1.88

(6) The distance 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 measured horizontally where the unprotected openings are on the same exposing building face, or

(b) 2 m measured vertically where the unprotected openings both serve,

(i) the single room or space, or

(ii) 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 sprinkleredand 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:

A_C = A + (A_F × F_EO)

where,

A_C = corrected area of unprotected openings including actual and equivalent openings,

A = actual area of unprotected openings,

A_F = area of exterior surface of the exposing building face, exclusive of openings, on which the temperature limit of the standard test is exceeded, and

F_EO = an equivalent opening factor derived from the following expression:

F_EO =

where,

T_u = average temperature in degrees Celsius of the unexposed wall surface at the time the required fire-resistance rating is reached under test conditions,

T_e = 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 buildingon his or her property unless the limiting distancefor 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 municipalityby 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 distancefor 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

Forming Part of Article 3.2.3.1.

Item	Exposing Building Face		Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, %
	Maximum Area, m2	Ratio (L/H or H/L)(1)	Limiting Distance, m
			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
1.	10	Less than 3:1	0	8	10	18	29	46	91	100
		3:1 to 10:1	0	8	12	21	33	50	96	100
		over 10:1	0	11	18	32	48	68	100
2.	15	Less than 3:1	0	7	9	14	22	33	63	100
		3:1 to 10:1	0	8	10	17	25	37	67	100
		over 10:1	0	10	15	26	39	53	87	100
3.	20	Less than 3:1	0	7	9	12	18	26	49	81	100
		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
4.	25	Less than 3:1	0	7	8	11	16	23	41	66	98	100
		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
5.	30	Less than 3:1	0	7	8	11	15	20	35	56	83	100
		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
6.	40	Less than 3:1	0	7	8	10	13	17	28	44	64	89	100
		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
7.	50	Less than 3:1	0	7	8	9	12	15	24	37	53	72	96	100
		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
8.	60	Less than 3:1	0	7	8	9	11	14	21	32	45	62	81	100
		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
9.	80	Less than 3:1	0	7	7	8	10	12	18	26	36	48	62	79	98	100
		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
10.	100	Less than 3:1	0	7	7	8	9	11	16	22	30	40	51	65	80	97	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
11.	150	Less than 3:1	0	7	7	8	9	10	13	17	22	29	37	46	56	67	79	93	100
		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
12.	250	Less than 3:1	0	7	7	7	8	9	10	13	16	20	25	30	36	43	51	59	68	87	100
		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
13.	350	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
		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
14.	500	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
		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
15.	1 000	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
		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
16.	2 000	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
		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 ofexposing 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

Forming Part of Article 3.2.3.1.

Notes to Table 3.2.3.1.C.:

⁽¹⁾ Apply whichever is greater,

L = Length ofexposing 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

Forming Part of Article 3.2.3.1.

Item	Exposing Building Face	Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, %
	Maximum Area, m2	Limiting Distance, m
		0	1.2	1.5	2	2.5	3	4	5	6	7	8	9
1,	10	0	16	24	42	66	100
2.	15	0	16	20	34	50	74	100
3.	20	0	16	20	30	42	60	100
4.	25	0	16	18	26	38	52	90	100
5.	30	0	14	18	24	34	46	78	100
6.	40	0	14	16	22	30	40	64	96	100
7.	50	0	14	16	20	28	36	56	82	100
8.	60	0	14	16	20	26	32	50	72	98	100
9.	80	0	14	16	18	22	28	42	58	80	100
10.	100	0	14	16	18	22	26	36	50	68	88	100
11.	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

Forming Part of Article 3.2.3.1.

Item	Exposing Building Face	Area of Unprotected Opening for Groups E and F, Division 1 and 2 Occupancies, %
	Maximum Area, m2	Limiting Distance, m
		0	1.2	1.5	2	2.5	3	4	5	6	7	8	9	10	11	12	13	14	15
1.	10	0	8	12	20	34	50	96	100
2.	15	0	8	10	16	26	36	68	100
3.	20	0	8	10	14	22	30	54	86	100
4.	25	0	8	10	14	18	26	44	70	100
5.	30	0	8	8	12	18	24	40	60	88	100
6.	40	0	8	8	12	16	20	32	48	68	94	100
7.	50	0	8	8	10	14	18	28	40	58	76	100
8.	60	0	8	8	10	12	16	24	36	50	66	86	100
9.	80	0	8	8	10	12	14	20	30	40	52	66	84	100
10.	100	0	8	8	8	10	12	18	26	34	44	56	70	84	100
11.	150	0	8	8	8	10	12	16	20	26	32	40	50	60	72	84	98	100
12.	200 or more	0	8	8	8	8	10	14	18	22	28	34	42	50	60	68	80	92	100