Classification, construction types and fire-resistance (3.1) (Complex Buildings)

Last updated October 22, 2026

Values this chapter turns on

firewall rating for Group E or F-1 or F-2 areas: 4 h; firewall rating for Group E or F-1 or F-2 areas
closure rating in a 1 h fire separation: 45 min; closure rating in a 1 h fire separation
max closure opening if either side is unsprinklered: 11 m²; max closure opening if either side is unsprinklered
parapet height above the roof for a 4 h firewall: 900 mm; parapet height above the roof for a 4 h firewall

Section 3.1. sets the vocabulary for the rest of Part 3: what a building is classified as, what it may be built of, and how fire separations, closures, firewalls and finishes are rated. Most Complex Buildings questions start here, because you cannot pick a construction article in 3.2.2. or a fire separation without first classifying the occupancy.

Classification by major occupancy and multiple occupancies

Every building, or part of one, gets a Group and Division from Table 3.1.2.1. (3.1.2.1.). A building with several major occupancies is classified for all of them. For this exam, know the Group B split by heart: Division 1 detention, Division 2 care and treatment, Division 3 care.

Special classification rules in 3.1.2.3. to 3.1.2.7.:

Use	Classification allowed
Arena used now and then for trade shows	Group A, Division 3 (3.1.2.3.)
Police station with detention quarters, 1 storey, up to 600 m²	Group B, Division 2 (3.1.2.4.)
Group B, Division 3 single housekeeping unit, up to 10 sleeping, no more than 2 needing help to evacuate	Group C (3.1.2.5.)
Storage of baled combustible fibres	medium-hazard industrial (3.1.2.6.)
Restaurant for up to 30 persons	Group E (3.1.2.7.)

Separating major occupancies. 3.1.3.1. sends you to Table 3.1.3.1.. Find the row for one occupancy and the column for the adjoining one. Patterns worth knowing: Group B, Division 1 needs 2 h from every occupancy it may adjoin; Group B, Divisions 2 and 3 need only 1 h from each other; Group D or E next to Group F, Division 1 needs 3 h. Group F, Division 1 may not share a building with any Group A, B or C occupancy (3.1.3.2.). A sleeping room may not open directly into a food area, and a building under 3.2.2.51. or 3.2.2.60. may not contain a retirement home.

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Combustible, noncombustible and encapsulated mass timber construction

Combustible construction may use combustible materials freely (3.1.4.1.). Heavy timber may replace combustible construction that needs a rating of 45 min or less (3.1.4.6.). Fire-retardant-treated wood must be pressure impregnated and have a flame-spread rating of 25 or less (3.1.4.5.).
Noncombustible construction uses noncombustible materials, with the permitted combustible components listed in 3.1.5.2. to 3.1.5.29. (3.1.5.1.). A material may also qualify through a cone calorimeter test at 50 kW/m²: total heat release of 3 MJ/m² or less and smoke extinction area of 1.0 m² or less. Combustible wall finishes up to 25 mm thick are allowed with flame-spread 150 or less. Ceiling finishes of that thickness need flame-spread 25, with 10% of each compartment's ceiling allowed at 150 (3.1.5.12.).
Encapsulated mass timber construction (EMTC) follows Subsection 3.1.6. (3.1.6.3., Table 3.1.6.3.). Minimum sizes include 96 mm for fire separation walls and floors, and 192 mm by 192 mm for beams and columns exposed on 2 or 3 sides. Encapsulation of at least 50 min applies under 3.2.2.48. and 3.2.2.57. (3.1.6.4.). Limited exposed timber is permitted, for example beams and columns up to 35% of the suite's perimeter wall area with flame-spread of 150 or less.

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Fire-resistance ratings, fire separations and closures

Ratings come from CAN/ULC-S101 tests or SB-2 (3.1.7.1.). Floors and roofs are rated from below, interior separations and firewalls from both sides, and exterior walls from inside (3.1.7.3.). Loadbearing walls, columns and arches under a rated floor need at least the floor's rating (3.1.7.5.).

A fire separation must be continuous, and openings need closures (3.1.8.1.). Table 3.1.8.4. pairs each separation rating with a closure rating. Selected pairs:

Fire separation	Closure
45 min or 1 h	45 min
1.5 h	1 h
2 h	1.5 h

Other closure rules:

Opening size (3.1.8.6.): at most 11 m² with no side over 3.7 m if either side is unsprinklered. With both sides sprinklered, the limit is 22 m² and 6 m.
20 min doors (3.1.8.12.) are allowed in separations of 1 h or less between a public corridor and a suite, or a corridor and sleeping rooms.
Self-closers are needed on doors in fire separations (3.1.8.13.). Hospitals and long-term care homes with compartments under 3.3.3.5. may omit them on patient sleeping room doors.
Hold-open devices may not be used on exit stair doors in buildings over 3 storeys (3.1.8.14.). Where there is a fire alarm system, those serving care, care and treatment or detention occupancies release on a smoke detector signal.

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Penetrations, firewalls and fire blocks

Penetrations are sealed with a firestop whose F rating is at least the separation's rating. Steel, copper, concrete or masonry items may be cast in place instead (3.1.9.1.). Firewalls and the 2 h storage garage separations need an FT rating.

Firewall essentials (3.1.10.2. to 3.1.10.5.):

Floor areas separated	Rating	Parapet
Group E, or Group F, Division 1 or 2	4 h	900 mm
Other occupancies	2 h	150 mm

A 2 h firewall need not be masonry or concrete in some cases. That relief is not available if it separates Group B, Division 1 or 2 floor areas, or a 3.2.6. building, unless both sides are sprinklered for the last case. Openings in a firewall total at most 25% of its length in each storey.

Fire blocks divide concealed wall spaces at each floor and at least every 20 m horizontally and 3 m vertically (3.1.11.2.). Unsprinklered combustible floor and roof spaces are divided into compartments of 600 m² (flame-spread 25 or less) or 300 m² (over 25) (3.1.11.5.).

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Flame spread, interior finish, roofs and fabrics

Ratings come from at least three CAN/ULC-S102 tests (3.1.12.1.). Walls and ceilings are limited to 150 generally, with tighter limits in Table 3.1.13.2. (3.1.13.2.):

Location	Sprinklered	Not sprinklered
Group A, Division 1; Group B	150	75
Exits, 3.4.4.2.(2) lobbies, vertical service spaces	25	25

Corridors used by the public in assembly or care occupancies, and corridors serving sleeping rooms in care, care and treatment or detention occupancies, have walls at 75 and ceilings at 25. If the floor area is sprinklered, both rise to 150 (3.1.13.6.). Doors may reach 200 except in Group A, Division 1. Roof coverings need Class A, B or C (3.1.15.2.), and awning fabrics are tested to CAN/ULC-S109 (3.1.16.1.).

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Occupant load, drainage, conductors and glass in guards

Occupant load for most floor areas comes from 3.1.17.1. A public pool uses its own formula (3.1.17.2.): deep water area (over 1,350 mm) divided by 2.5, plus shallow area divided by 1.4.

The site is graded so water does not pond at the building or harm neighbours (3.1.19.1.). Buildings may not go under overhead conductors. Clearance from the conductor's swing is at least 1 m for 750 V or less, 3 m up to 46 kV and 3.7 m up to 69 kV (3.1.20.1.). Glass in guards follows SB-13 (3.1.21.1.).

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Common traps

Reading Table 3.1.3.1. from the wrong row. It is symmetric for most pairs, but check the notes.
Using the 1 h closure rating for a 1 h separation. The closure is 45 min.
Giving a firewall between offices a 4 h rating. 4 h is triggered only by Group E or Group F, Division 1 or 2.
Applying the 150 corridor limit without full sprinklering of the floor area.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Fire-resistance ratings, fire separations and closures	Ratings come from CAN/ULC-S101 tests or SB-2. Floors and roofs are rated from below, interior separations and firewalls from both sides, and exterior walls from inside.
Penetrations, firewalls and fire blocks	Penetrations are sealed with a firestop whose F rating is at least the separation's rating.
Flame spread, interior finish, roofs and fabrics	Ratings come from at least three CAN/ULC-S102 tests.
Occupant load, drainage, conductors and glass in guards	Occupant load for most floor areas comes from 3.1.17.1. A public pool uses its own formula: deep water area (over 1,350 mm) divided by 2.5, plus shallow area divided by 1.4.

Fire-resistance ratings, fire separations and closures
Ratings come from CAN/ULC-S101 tests or SB-2. Floors and roofs are rated from below, interior separations and firewalls from both sides, and exterior walls from inside.
Penetrations, firewalls and fire blocks
Penetrations are sealed with a firestop whose F rating is at least the separation's rating.
Flame spread, interior finish, roofs and fabrics
Ratings come from at least three CAN/ULC-S102 tests.
Occupant load, drainage, conductors and glass in guards
Occupant load for most floor areas comes from 3.1.17.1. A public pool uses its own formula: deep water area (over 1,350 mm) divided by 2.5, plus shallow area divided by 1.4.

Usual exam traps

Reading Table 3.1.3.1. from the wrong row. It is symmetric for most pairs, but check the notes.
Using the 1 h closure rating for a 1 h separation. The closure is 45 min.
Giving a firewall between offices a 4 h rating. 4 h is triggered only by Group E or Group F, Division 1 or 2.
Applying the 150 corridor limit without full sprinklering of the floor area.

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Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B Table 3.1.2.1. Major Occupancy Classification
Table 3.1.2.1. Major Occupancy Classification Forming Part of Sentences 3.1.2.1.(1), 3.1.2.2.(1) and 3.11.2.1.(3) Group | Division | Description of Major Occupancy A | 1 | Assembly occupancies intended for the production and viewing of the performing arts A | 2 | Assembly occupancies not elsewhere classified in Group A A | 3 | Assembly occupancies of the arena type A | 4 | Assembly occupancies in which occupants are gathered in the open air B | 1 | Detention occupancies B | 2 | Care and treatment occupancies B | 3 | Care occupancies C | N/A | Residential occupancies D | N/A | Business and personal services occupancies E | N/A | Mercantile occupancies F | 1 | High-hazard industrial occupancies F | 2 | Medium-hazard industrial occupancies F | 3 | Low-hazard industrial occupancies
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OBC Div. B 3.1.2.1. Classification of Buildings
(1)Except as permitted by Articles 3.1.2.3. to 3.1.2.7., every building or part thereof shall be classified according to its major occupancy as belonging to one of the Groups or Divisions described in Table 3.1.2.1. (See Note A-3.1.2.1.(1))
(2)A building intended for use by more than one major occupancy shall be classified according to all major occupancies for which it is used or intended to be used.
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OBC Div. B 3.1.2.3. Arena-Type Buildings
(1)An arena-type building intended for occasional use for trade shows and similar exhibition purposes shall be classified as Group A, Division 3 occupancy.
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OBC Div. B 3.1.2.4. Police Stations
(1)A police station with detention quarters is permitted to be classified as a Group B, Division 2 major occupancy provided the station is not more than 1 storey in building height and 600 m² in building area.
Open OBC Div. B 3.1.2.4. in the code viewer
OBC Div. B 3.1.2.5. Group B, Division 3 Occupancies
(1)Group B, Division 3 occupancies are permitted to be classified as Group C major occupancies within the application of Part 3 provided
(a)the occupants live as a single housekeeping unit in a suite with sleeping accommodation for not more than 10 persons, and
(b)not more than two occupants require assistance in evacuation in case of an emergency.
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OBC Div. B 3.1.2.6. Storage of Combustible Fibres
(1)Buildings or parts of thereof used for the storage of baled combustible fibres shall be classified as medium-hazard industrial occupancies.
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OBC Div. B 3.1.2.7. Restaurants
(1)A restaurant is permitted to be classified as a Group E major occupancy within the application of Part 3 provided the restaurant is designed to accommodate not more than 30 persons consuming food or drink.
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OBC Div. B 3.1.3.1. Separation of Major Occupancies
(1)Except as permitted by Sentences (2) and (3), major occupancies shall be separated from adjoining major occupancies by fire separations having fire-resistance ratings conforming to Table 3.1.3.1.
(2)In a building not more than 3 storeys in building height, if not more than two dwelling units are contained together with a Group E major occupancy, the fire-resistance rating of the fire separation between the two major occupancies need not be more than 1 h.
(3)In a building conforming to the requirements of Articles 3.2.8.2. to 3.2.8.8., the requirements of Sentence (1) for fire separations between major occupancies do not apply at the vertical plane around the perimeter of an opening through the horizontal fire separation.
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OBC Div. B Table 3.1.3.1. Major Occupancy Fire Separations—Minimum Fire-Resistance Rating of Fire Separation, h[1]
Table 3.1.3.1. Major Occupancy Fire Separations—Minimum Fire-Resistance Rating of Fire Separation, h[1] Forming Part of Sentence 3.1.3.1.(1) Major Occupancy | Adjoining Major Occupancy A-1 | Adjoining Major Occupancy A-2 | Adjoining Major Occupancy A-3 | Adjoining Major Occupancy A-4 | Adjoining Major Occupancy B-1 | Adjoining Major Occupancy B-2 | Adjoining Major Occupancy B-3 | Adjoining Major Occupancy C | Adjoining Major Occupancy D | Adjoining Major Occupancy E | Adjoining Major Occupancy F-1 | Adjoining Major Occupancy F-2 | Adjoining Major Occupancy F-3 A-1 | N/A | 1 | 1 | 1 | 2 | 2 | 2 | 1 | 1 | 2 | [2] | 2 | 1 A-2 | 1 | N/A | 1 | 1 | 2 | 2 | 2 | 1[3] | 1[4] | 2 | [2] | 2 | 1 A-3 | 1 | 1 | N/A | 1 | 2 | 2 | 2 | 1 | 1 | 2 | [2] | 2 | 1 A-4 | 1 | 1 | 1 | N/A | 2 | 2 | 2 | 1 | 1 | 2 | [2] | 2 | 1 B-1 | 2 | 2 | 2 | 2 | N/A | 2 | 2 | 2 | 2 | 2 | [2] | 2 | 2 B-2 | 2 | 2 | 2 | 2 | 2 | N/A | 1 | 2 | 2 | 2 | [2] | 2 | 2 B-3 | 2 | 2 | 2 | 2 | 2 | 1 | N/A | 2 | 2 | 2 | [2] | 2 | 2 C | 1 | 1[3] | 1 | 1 | 2 | 2 | 2 | N/A | 1 | 2[5] | [2] | 2[6] | 1 D | 1 | 1[4] | 1 | 1 | 2 | 2 | 2 | 1 | N/A | N/A | 3 | N/A | N/A E | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2[5] | N/A | N/A | 3 | N/A | N/A F-1 | [2] | [2] | [2] | [2] | [2] | [2] | [2] | [2] | 3 | 3 | N/A | 2 | 2 F-2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2[6] | N/A | N/A | 2 | N/A | N/A F-3 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 1 | N/A | N/A | 2 | N/A | N/A Notes to Table 3.1.3.1.: (1) Section 3.3. contains requirements for the separation of occupancies and tenancies that are in addition to the requirements for the separation of major occupancies. (2) See Sentence 3.1.3.2.(1). (3) Where the building or part thereof is constructed in accordance with Article 3.2.2.51., a fire separation with a 2 h fire-resistance rating is required between the Group C and Group A, Division 2 major occupancies. (4) Where the building or part thereof is constructed in accordance with Article 3.2.2.60., a fire separation with a 2 h fire-resistance rating is required between the Group D and Group A, Division 2 major occupancies. (5) See Sentence 3.1.3.1.(2). (6) See Sentence 3.1.3.2.(2).
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OBC Div. B 3.1.3.2. Prohibition of Occupancy Combinations
(1)No major occupancy of Group F, Division 1 shall be contained within a building with any occupancy classified as Group A, B or C.
(2)Except as provided in Sentence (4) and Sentence 3.10.2.4.(9), not more than one suite of residential occupancy shall be contained within a building classified as a Group F, Division 2 major occupancy.
(3)A sleeping room or sleeping area shall not open directly into a room or area where food is intended to be stored, prepared, processed, distributed, served, sold or offered for sale. (See Note A-3.1.3.2.(3))
(4)A Group F, Division 2 major occupancy is permitted in a building containing only live/work units if the occupancy is for the exclusive use of the occupants of the live/work units.
(5)A building within the scope of Article 3.2.2.51. or 3.2.2.60. shall not contain a retirement home.
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OBC Div. B 3.1.4.1. Combustible Materials Permitted
(1)A building permitted to be of combustible construction is permitted to be constructed of combustible materials, with or without noncombustible components. (See Note A-3.1.4.1.(1))
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OBC Div. B 3.1.4.6. Heavy Timber Construction Alternative
(1)If combustible construction is permitted and is not required to have a fire-resistance rating more than 45 min, heavy timber construction is permitted to be used.
(2)If heavy timber construction is permitted, it shall conform to Article 3.1.4.7.
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OBC Div. B 3.1.4.5. Fire-Retardant-Treated Wood
(1)If fire-retardant-treated wood is specified in this Part, the wood shall
(a)be pressure impregnated with fire-retardant chemicals in conformance with CAN/CSA-O80 Series, "Wood preservation," and
(b)have a flame-spread rating not more than 25.
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OBC Div. B 3.1.5.1. Noncombustible Materials)
(1)Except as permitted by Sentences (2) to (4) and Articles 3.1.5.2. to 3.1.5.29., 3.1.13.4. and 3.2.2.16., a building or part of a building required to be of noncombustible construction, shall be constructed with noncombustible materials. (See also Subsection 3.1.13. for the requirements regarding the flame-spread rating of interior finishes.)
(2)Notwithstanding the definition of noncombustible materials stated in Article 1.4.1.2. of Division A, a material is permitted to be used in noncombustible construction provided that, when tested in accordance with ULC S135, "Standard Test Method for the Determination of Combustibility Parameters of Building Materials Using an Oxygen Consumption Calorimeter (Cone Calorimeter)", at a heat flux of 50 kW/m²,
(a)its average total heat release is not more than 3 MJ/m²,
(b)its average total smoke extinction area is not more than 1.0 m², and
(c)the test duration is extended beyond the time stipulated in the referenced standard until it is clear that there is no further release of heat or smoke.
(3)If a material referred to in Sentence (2) consists of a number of discrete layers and testing reveals that the surface layer or layers protect the underlying layers such that complete combustion of the underlying layers does not occur, the test shall be repeated by removing the outer layers sequentially until all layers have been exposed during testing, or until complete combustion has occurred.
(4)The acceptance criteria for a material tested in accordance with Sentence (3) shall be based on the cumulative emissions from all layers, which must not exceed the criteria stated in Clauses (2)(a) and (b).
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OBC Div. B 3.1.5.12. Combustible Interior Finishes
(1)Except permitted in Sentences (2) and (3), combustible interior wall and ceiling finishes referred to in Clause 3.1.13.1.(2)(b) that are not more than 1 mm thick are permitted in a building required to be of noncombustible construction.
(2)Combustible interior wall finishes, other than foamed plastics, that are not more than 25 mm thick are permitted in a building required to be of noncombustible construction, provided they have a flame-spread rating not more than 150 on any exposed surface or any surface that would be exposed by cutting through the material in any direction.
(3)Except as provided in Sentence (4), combustible interior ceiling finishes, other than foamed plastics, that are not more than 25 mm thick are permitted in a building required to be of noncombustible construction, provided they have a flame-spread rating not more than 25 on any exposed surface or on any surface that would be exposed by cutting through the material in any direction, except that not more than 10% of the ceiling area within each fire compartment is permitted to have a flame-spread rating not more than 150.
(4)Combustible interior ceiling finishes made of fire-retardant-treated wood are permitted in a building required to be of noncombustible construction, provided they are not more than 25 mm thick or are exposed fire-retardant-treated wood battens.
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OBC Div. B 3.1.6.3. Structural Mass Timber Elements
(1)Except as otherwise provided in this Subsection and Articles 3.2.2.16. and 3.2.3.19., a building or part of a building permitted to be of encapsulated mass timber construction is permitted to include structural mass timber elements, including beams, columns, arches and wall, floor and roof assemblies, provided they comply with Sentences (2) and (3).
(2)Structural mass timber elements referred to in Sentence (1) shall
(a)except as provided in Sentence (4), be arranged in heavy solid masses containing no concealed spaces,
(b)have essentially smooth flat surfaces with no thin sections or sharp projections, and
(c)except as provided in Sentence 3.1.6.17.(1), conform to the minimum dimensions stated in Table 3.1.6.3.
(3)Adhesives used in structural mass timber elements referred to in Sentence (1) that are constructed of cross-laminated timber shall conform to the elevated temperature performance requirements in ANSI/APA PRG 320, "Standard for Performance-Rated Cross-Laminated Timber."
(4)Concealed spaces are permitted within structural mass timber elements referred to in Sentence (2) and need not conform to Sentence 3.1.6.4.(1) provided the concealed spaces are,
(a)sprinklered and divided into compartments by fire blocks in conformance with Subsection 3.1.11.,
(b)completely filled with rock or slag fibre insulation conforming to CAN/ULC-S702.1 "Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1: Material Specification," and having a density not less than 32 kg/m²,
(c)if horizontal, lined with not less than a single layer of 12.7 mm thick Type X gypsum board or noncombustible material providing an encapsulation rating of not less than 25 min, or
(d)if vertical, lined with not less than a single layer of 12.7 mm thick Type X gypsum board or noncombustible material providing an encapsulation rating of not less than 25 min and vertically divided into compartments by fire blocks in conformance with Subsection 3.1.11.
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OBC Div. B Table 3.1.6.3. Minimum Dimensions of Structural Mass Timber Elements in Encapsulated Mass Timber Construction
Table 3.1.6.3. — Minimum Dimensions of Structural Mass Timber Elements in Encapsulated Mass Timber Construction Forming Part of Sentences 3.1.6.3.(2), 3.1.6.8.(1) and 3.1.6.17.(1) Structural Wood Elements | Minimum Thickness, mm | Minimum Width x Depth, mm x mm Walls that are fire separations or exterior walls (1-sided fire exposure) | 96 | N/A Walls that require a fire-resistance rating, but are not fire separations (2-sided fire exposure) | 192 | N/A Floors[1] and roofs (1-sided fire exposure) | 96 | N/A Beams, columns and arches (2- or 3-sided fire exposure) | N/A | 192 x 192 Beams, columns and arches (4-sided fire exposure) | N/A | 224 x 224 Notes to Table 3.1.6.3.: (1) The minimum dimensions for floor assemblies are also applicable to mezzanines and exterior balconies.
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OBC Div. B 3.1.6.4. Encapsulation of Mass Timber Elements
(1)Except as provided in Sentences (3) to (9), 3.1.6.3.(4), 3.1.6.16.(2) and 3.1.6.17.(2), and Articles 3.1.6.7. and 3.1.6.12., the exposed surfaces of structural mass timber elements conforming to Article 3.1.6.3. shall be protected from adjacent spaces in the building, including adjacent concealed spaces within wall, floor and roof assemblies, by a material or assembly of materials conforming to Sentence (2) that provides an encapsulation rating that
(a)is not less than 50 min in a building or part thereof constructed in conformance with Article 3.2.2.48. or 3.2.2.57., or
(b)conforms to the minimum values stated in Table 3.2.2.93. for the applicable major occupancy and building height. (See Note A-3.1.6.4.(1))
(1) (1) Except as provided in Sentence 3.1.6.11.(1), the material or assembly of materials referred to Sentence (1) shall consist of
(a) gypsum board,
(b) gypsum concrete,
(c)noncombustible materials,
(d)materials that conform to Sentences 3.1.5.1.(2) to (4), or
(e)any combination of materials listed in Clauses (a) to (d).
(3) Except as provided in Sentences (5) and (7), the exposed surfaces of mass timber beams, columns and arches within a suite or fire compartment in a building or part thereof constructed in conformance with Article 3.2.2.48. or 3.2.2.57. or permitted by Article 3.2.2.93. to have a 50 min encapsulation rating need not be protected in accordance with Sentence (1), provided
(a) their aggregate exposed surface area does not exceed 35% of the total wall area of the perimeter of the suite or fire compartment in which they are located, and
(b) the flame-spread rating on any exposed surface is not more than 150. (See Note A-3.1.6.4.(3) to (8))
(2)Except as provided in Sentences (5) to (7), the exposed surfaces of mass timber walls within a suite in a building or part threreof constructed in conformance with Article 3.2.2.48. or 3.2.2.57. or permitted by Article 3.2.2.93. to have a 50 min encapsulation rating need not be protected in accordance with Sentence (1), provided
(a)all portions of the exposed surfaces,
(i)face the same direction, or
(ii)are separated by a horizonal distance of not less than 4.5 m, and
(b)the flame-spread rating on any exposed surface is not more than 150. (See Notes A-3.1.6.4.(4) and A-3.1.6.4(3) to (8))
(3)Except as provided in Sentence (7), the aggregate exposed surface area of mass timber elements within a suite permitted in Sentences (3) and (4) shall not exceed 35% of the total wall area of the perimeter of the suite. (See Note A-3.1.6.4.(3) to (8))
(6) Except as provided in Sentence (7), the exposed surfaces of mass timber ceilings within a suite or fire compartment, other than an exit and public corridor, in a building or part thereof constructed in conformance with Article 3.2.2.48. or 3.2.2.57. or permitted by Article 3.2.2.93. to have a 50 min encapsulation rating need not be protected in accordance with Sentence (1), provided the aggregate surface area does not exceed
(a)10% of the total ceiling area of the suite or fire compartment, where the flame-spread rating on any exposed surface is not more than 150, or
(b)25% of the total ceiling area of the suite or fire compartment, where the flame-spread rating on any exposed surface of a mass timber wall or ceiling is not more than 75. (See Note A-3.1.6.4.(3) to (8))
(7) The exposed surfaces of mass timber ceilings within a suite in a building or part thereof constructed in conformance with Article 3.2.2.48. or 3.2.2.57. or permitted by Article 3.2.2.93. to have a 50 min encapsulation rating need not be protected in accordance with Sentence (1) or (6), provided
(a) the aggregate surface area of any exposed mass timber beams, columns and arches does not exceed 20% of the total wall area of the perimeter of the suite in which they are located,
(b) all surface of the mass timber walls are,
(i)protected in accordance with Sentence (1), or
(ii)mass timber walls that are not otherwise permitted to be exposed in accordance with Sentence (5) are protected by a material or assembly of materials conforming to Sentence (2) that provides an encapsulation rating of not less than 80 min, and
(c)the flame spread rating on any exposed mass timber wall or ceiling is not more than 75. (See Note A-3.1.6.4.(3) to (8))
(8) Structural mass timber elements in a building or part thereof permitted by Article 3.2.2.93. to have a 0 min encapsulation rating need not be protected in accordance with Sentence (1), provided
(a) mass timber walls and ceilings within vertical service spaces, public corridors, and exits are protected on the interior side with a material or assembly of materials conforming to Sentence (2) that provides an encapsulation rating of not less than 25 min, and
(b) concealed spaces are protected in conformance with Sentence 3.1.6.3.(4). (See Note A-3.1.6.4.(3) to (8))
(9) In a building or part thereof required by Clause 3.1.6.4.(1)(b) to have a minimum encapsulation rating of 70 min, the upper side of a mass timber floor or roof assembly is permitted to be encapsulated by a material or assembly of materials conforming to Sentence 3.1.6.4.(2) that provides an encapsulation rating of 50 min.
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OBC Div. B 3.1.7.1. Determination of Ratings
(1)Except as permitted by Sentence (2) and Articles 3.1.7.2. and 3.6.3.5., the rating of a material, assembly of materials or a structural member that is required to have a fire-resistance rating, shall be determined on the basis of the results of tests conducted in conformance with CAN/ULC-S101, "Standard Method of Fire Endurance Tests of Building Construction and Materials."
(2)A material, assembly of materials or a structural member is permitted to be assigned a fire-resistance rating on the basis of MMAH Supplementary Standard SB-2, "Fire Performance Ratings."
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OBC Div. B 3.1.7.3. Exposure Conditions for Rating
(1)Floor, roof and ceiling assemblies shall be rated for exposure to fire on the underside.
(2)Firewalls and interior vertical fire separations shall be rated for exposure to fire on each side.
(3)Exterior walls shall be rated for exposure to fire from inside the building.
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OBC Div. B 3.1.7.5. Rating of Supporting Construction
(1)Except as permitted by Sentence (2) and by Articles 3.2.2.20. to 3.2.2.93. for mixed types of construction, all loadbearing walls, columns and arches in the storey immediately below a floor or roof assembly required to have a fire-resistance rating shall have a fire-resistance rating not less than that required for the supported floor or roof assembly.
(2)Loadbearing walls, columns and arches supporting a service room or service space need not conform to Sentence (1).
(3)Except as provided in Sentence (4) and except for noncombustible roof assemblies required by Clauses 3.2.2.51.(2)(c) and 3.2.2.60.(2)(c), if an assembly is required to be of noncombustible construction and have a fire-resistance rating, it shall be supported by noncombustible construction.
(4)Except for portions of a building constructed in accordance with Article 3.2.2.7. that are required to be of noncombustible construction, assemblies of noncombustible construction in buildings or portions of buildings permitted to be of encapsulated mass timber construction are permitted to be supported by encapsulated mass timber construction.
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OBC Div. B 3.1.8.1. General Requirements
(1)Any wall, partition or floor assembly required to be a fire separation shall
(a)except as permitted by Sentence (2), be constructed as a continuous element in conformance with Article 3.1.8.3., and
(b)as required in this Part, have a fire-resistance rating as specified. (See Note A-3.1.8.1.(1)(b))
(2)Openings in a fire separation shall be protected with closures, shafts or other means in conformance with Articles 3.1.8.4. to 3.1.8.20. and Subsections 3.1.9. and 3.2.8. (See Note A-3.1.8.1.(2))
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OBC Div. B Table 3.1.8.4. Fire-Protection Rating of Closures
Table 3.1.8.4. — Fire-Protection Rating of Closures Forming Part of Sentence 3.1.8.4.(2) Fire Separation | Closure 30 min | 20 min 45 min | 45 min 1 h | 45 min 1.5 h | 1 h 2 h | 1.5 h 3 h | 2 h 4 h | 3 h
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OBC Div. B 3.1.8.6. Maximum Openings
(1)The size of an opening in an interior fire separation required to be protected with a closure shall be not more than 11 m², with no dimension more than 3.7 m, if a fire compartment on either side of the fire separation is not sprinklered.
(2)The size of an opening in an interior fire separation required to be protected with a closure shall be not more than 22 m², with no dimension more than 6 m, provided the fire compartments on both sides of the fire separation are sprinklered.
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OBC Div. B 3.1.8.12. Twenty-Minute Closures
(1)A door assembly having a fire-protection rating not less than 20 min is permitted to be used as a closure in
(a)a fire separation not required to have a fire-resistance rating more than 1 h, located between
(i)a public corridor and a suite,
(ii)a corridor and adjacent sleeping rooms, or
(iii)a corridor and adjacent classrooms, offices and libraries in Group A, Division 2 major occupancies, or
(b)a fire separation not required to have a fire-resistance rating more than 45 min, located in a building not more than 3 storeys in building height.
(2)The requirements for noncombustible sills and combustible floor coverings in NFPA 80, "Standard for Fire Doors and Other Opening Protectives," do not apply to a door described in Sentence (1).
(3)A door described in Sentence (1) shall have clearances of not more than 6 mm at the bottom and not more than 3 mm at the sides and top.
(4)In elementary and secondary schools, a door assembly conforming to Articles 9.10.13.2. and 9.10.13.3. is permitted to be used as a closure in a fire separation having a fire-resistance rating of 30 min.
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OBC Div. B 3.1.8.13. Self-Closing Devices
(1)Except as provided in Sentences (3) to (5) and 3.3.3.2.(5), every door in a fire separation, other than doors to freight elevators and dumbwaiters, shall be equipped with a self-closing device designed to return the door to the closed position after each use.
(2)Reserved.
(3)In a building that is not more than 3 storeys in building height, a self-closing device is not required on a door that is located between a classroom and a corridor providing access to exit from the classroom, except that a self-closing device is required on a door between a hazardous classroom and the corridor in an elementary or secondary school.
(4)In a building that is not more than 3 storeys in building height, a self-closing device is not required on a door between a public corridor and an adjacent room or suite of business and personal services occupancy if the door is not located in.
(a)a dead-end portion of the corridor, or
(b)a corridor that serves a hotel.
(5)Within a fire compartment in a hospital or long-term care home that complies with the requirements of Article 3.3.3.5., a self-closing device is not required on a door that is located between
(a)a patient's or resident's sleeping room and a corridor serving the patient's or resident's sleeping room, or
(b)a patient's or resident's sleeping room and an adjacent room that serves the patient's or resident's sleeping room.
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OBC Div. B 3.1.8.14. Hold-Open Devices
(1)Except as provided in Sentences 3.1.8.10.(2) and 3.1.8.11.(3), a hold-open device is permitted to be used on a closure in a required fire separation, other than on an exit stair door in a building more than 3 storeys in building height and on a door for a vestibule required by Article 3.3.5.7., provided the device is designed to release the closure in conformance with this Article.
(2)Except as provided in Sentences (5) and (6), where the building is provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release
(a)in a single-stage system, upon any signal from the fire alarm system, and
(b)in a 2-stage system,
(i)upon any alert signal from the fire alarm system, or
(ii)upon actuation of any adjacent smoke detectors.
(3)Where the building is provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release upon a signal from a smoke detector connected to the fire alarm system and located as described in CAN/ULC-S524, "Standard for Installation of Fire Alarm Systems," where the hold-open device is used on
(a)an exit door,
(b)a door opening into a public corridor,
(c)an egress door referred to in Sentence 3.4.2.4.(2),
(d)a closure serving an assembly, care, care and treatment, detention, or residential occupancy,
(e)a door in a fire separation referred to in Clause 3.3.1.7.(1)(b) or Sentence 3.3.3.5.(4) or 3.3.4.11.(4), or
(f)a door required to function as part of a smoke control system.
(4)Where the building is not provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release upon a signal from a smoke alarm located on either side of the fire separation at ceiling level within 1.5 m horizontally of the closure opening in the fire separation, where the hold-open device is used on closures described in Clauses (3)(a) to (e).
(5)Where a hold-open device is used on closures other than those described in Sentences (3) and (4), it is permitted to be released upon actuation of a heat-actuated device.
(6)A hold-open device used on a door located between a corridor used by the public and an adjacent sleeping room in a care and treatment occupancy need not release automatically as stated in Sentence (2).
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OBC Div. B 3.1.9.1. Firestops
(1)Except as provided in Sentences (2) to (7) and Article 3.1.9.3., penetrations of a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating shall be
(a)sealed by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the required fire-resistance rating of the fire separation, or
(b)cast-in-place, where the item penetrating the fire separation is steel, ferrous, copper, concrete or masonry. (See Note A-3.1.9.1.(1)(b))
(See also Article 3.1.9.4. for requirements regarding penetrations by combustible drain, waste and vent piping.)
(2)Except as permitted in Sentence (6), penetrations of a firewall or a horizontal fire separation that is required to have a fire-resistance rating in conformance with Article 3.2.1.2. shall be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an FT rating not less than the fire-resistance rating for the fire separation.
(3)Except as permitted in Sentences (6) and (7), penetrations of a fire separation in conformance with Sentence 3.6.4.2.(2) shall be sealed by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an FT rating not less than the fire-resistance rating for the fire separation of the assembly.
(4)Sprinklers are permitted to penetrate a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating without having to meet the firestop requirements of Sentences (1) to (3), provided the annular space created by the penetration of a fire sprinkler is covered by a metal escutcheon plate in accordance with NFPA 13, "Standard for the Installation of Sprinkler Systems."
(5)Unless specifically designed with a firestop, fire dampers are permitted to penetrate a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating without having to meet the firestop requirements of Sentences (1) to (3), provided the fire damper is installed in conformance with NFPA 80, "Standard for Fire Doors and Other Opening Protectives."
(6)Service equipment penetrations through a horizontal fire separation having a fire-resistance rating as described in Sentences (2) and (3) that are contained within the cavity of a wall above and below the horizontal fire separation are permitted to be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the fire-resistance rating for the fire separation.
(7)Service equipment penetrations through a horizontal fire separation having a fire-resistance rating as described in Sentence (3) are permitted to be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the fire-resistance rating for the fire separation, provided the penetration
(a)is contained within the concealed space of a floor or ceiling assembly having a fire-resistance rating,
(b)is located above a ceiling membrane that is a horizontal fire separation, or
(c)is contained within a horizontal service space conforming to Subsection 3.6.4. that is directly above or below the floor.
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OBC Div. B 3.1.10.2. Rating of Firewalls
(1)A firewall that separates a building or buildings with floor areas containing a Group E or a Group F, Division 1 or 2 major occupancy shall be constructed as a fire separation of noncombustible construction having a fire-resistance rating not less than 4 h, except that where the upper portion of a firewall separates floor areas containing other than Group E or Group F, Division 1 or 2 major occupancies, the fire-resistance rating of the upper portion of the firewall is permitted to be not less than 2 h.
(2)A firewall that separates a building or buildings with floor areas containing major occupancies other than Group E or Group F, Division 1 or 2 shall be constructed as a fire separation of noncombustible construction having a fire-resistance rating not less than 2 h.
(3)Except as permitted by Sentence (4), the required fire-resistance rating of a firewall, except for closures, shall be provided by masonry or concrete.
(4)A firewall permitted to have a fire-resistance rating not more than 2 h need not be constructed of masonry or concrete provided
(a)the assembly providing the fire-resistance rating is protected against damage that would compromise the integrity of the assembly,
(b)the design conforms to Article 4.1.5.17.,
(c)the level of performance of the firewall is not less than of masonry or concrete in the areas of
(i)performance during fire conditions,
(ii)mechanical damage during the normal use of the building, and
(iii)resistance to damage from moisture,
(d)the firewall separates buildings or buildings with floor areas that do not contain
(i)a Group B, Division 1 major occupancy, or
(ii)a Group B, Division 2 major occupancy, and
(e)the firewall does not separate a building regulated by the provisions of Subsection 3.2.6. or a building within the scope of Article 3.2.2.51. or 3.2.2.60. from another building unless the buildings on both sides of the firewall are sprinklered. (See Note A-3.1.10.2.(4))
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OBC Div. B 3.1.10.5. Maximum Openings
(1)Openings in a firewall shall conform to the size limits described in Article 3.1.8.6.
(2)The aggregate width of openings in a firewall within a storey shall be not more than 25% of the entire length of the firewall.
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OBC Div. B 3.1.11.2. Fire Blocks in Wall Assemblies
(1)Except as permitted by Sentence (2), fire blocks conforming to Article 3.1.11.7. shall be provided to block off concealed spaces within a wall assembly
(a)at every floor level,
(b)at every ceiling level where the ceiling forms part of an assembly required to have a fire-resistance rating, and
(c)so that the maximum horizontal dimension is not more than 20 m and the maximum vertical dimension is not more than 3 m.
(2)Fire blocks conforming to Sentence (1) are not required provided
(a)the wall space is filled with insulation,
(b)the exposed construction materials and any insulation within the wall space are noncombustible,
(c)the exposed materials within the wall space, including insulation but not including wiring, piping or similar services, have a flame-spread rating not more than 25 on any exposed surface, or on any surface that would be exposed by cutting through the material in any direction, and fire blocks are installed so that the vertical distance between them is not more than 10 m, or
(d)the insulated wall assembly contains not more than one concealed air space, and the horizontal thickness of that air space is not more than 25 mm.
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OBC Div. B 3.1.11.5. Fire Blocks in Horizontal Concealed Spaces
(1)Except for crawl spaces conforming to Sentence 3.1.11.6.(1) and as required in Sentence (3), horizontal concealed spaces within a floor assembly or roof assembly of combustible construction, in which sprinklers are not installed, shall be separated by construction conforming to Article 3.1.11.7. into compartments
(a)not more than 600 m² in area with no dimension more than 60 m, if the exposed construction materials within the space have a flame-spread rating not more than 25, and
(b)not more than 300 m² in area with no dimension more than 20 m, if the exposed construction materials within the space have a flame-spread rating more than 25.
(See Note A-3.1.11.5.(1))
(2)A concealed space in an exterior cornice, a mansard style roof, a balcony or a canopy in which exposed construction materials within the space have a flame-spread rating more than 25, shall be separated by construction conforming to Article 3.1.11.7.
(a)at locations where the concealed space extends across the ends of required vertical fire separations, and
(b)so that the maximum dimension in the concealed space is not more than 20 m.
(3)Except as provided by Sentence (5), in buildings or parts thereof conforming to Article 3.2.2.51. or 3.2.2.60., horizontal concealed spaces within a floor assembly or roof assembly of combustible construction shall be separated by construction conforming to Article 3.1.11.7. into compartments that are
(a)not more than 600 m² in area with no dimension more than 60 m, if the exposed construction materials within the space have a flame-spread rating not more than 25, and
(b)not more than 300 m² in area with no dimension more than 20 m, if the exposed construction materials within the space have a flame-spread rating more than 25. (See Note A-3.1.11.5.(3) and (4))
(4)Except for crawl spaces conforming to Sentence 3.1.11.6.(1) and except as provided in Sentence (5), in buildings or parts thereof conforming to Article 3.2.2.48., 3.2.2.57. or 3.2.2.93., horizontal concealed spaces within a floor assembly or roof assembly of encapsulated mass timber construction shall be separated by construction conforming to Article 3.1.11.7. into compartments that are
(a)not more than 600 m² in area with no dimension more than 60 m, if the exposed construction materials within the space have a flame-spread rating not more than 25, and
(b)not more than 300 m² in area with no dimension more than 20 m, if the exposed construction materials within the space have a flame-spread rating more than 25. (See Note A-3.1.11.5.(3) and (4))
(5)Fire blocks conforming to Sentences (3) and (4) are not required where the horizontal concealed space within the floor or roof assembly is entirely filled with noncombustible insulation such that any air gap between the top of the insulation and the floor or roof deck does not exceed 50 mm.
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OBC Div. B 3.1.12.1. Determination of Ratings
(1)Except as required by Sentence (2) and as permitted by Sentence (3), the flame-spread rating and smoke developed classification of a material, assembly, or structural member shall be determined on the basis of not less than three tests conducted in conformance with CAN/ULC-S102, "Standard Method of Test for Surface Burning Characteristics of Building Materials and Assemblies."
(2)The flame-spread rating and smoke developed classification of a material or assembly shall be determined on the basis of not less than three tests conducted in conformance with CAN/ULC-S102.2, "Standard Method of Test for Surface Burning Characteristics of Flooring, Floor Coverings, and Miscellaneous Materials and Assemblies," if the material or assembly
(a)is designed for use in a relatively horizontal position with only its top surface exposed to air,
(b)cannot be tested in conformance with Sentence (1) without the use of supporting material that is not representative of the intended installation, or
(c)is thermoplastic.
(3)A material, assembly, or structural member is permitted to be assigned a flame-spread rating and smoke developed classification on the basis of MMAH Supplementary Standard SB-2, "Fire Performance Ratings."
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OBC Div. B Table 3.1.13.2. Flame-Spread Ratings
Table 3.1.13.2. Flame-Spread Ratings Forming Part of Sentence 3.1.13.2.(1) Occupancy, Location or Element | Maximum Flame-Spread Rating — Sprinklered Walls and Ceilings | Maximum Flame-Spread Rating — Not Sprinklered Walls and Ceilings Group A, Division 1 occupancies, including doors, skylights, glazing and light diffusers and lenses | 150 | 75 Group B occupancies | 150 | 75 Exits[1] | 25 | 25 Lobbies described in Sentence 3.4.4.2.(2) | 25 | 25 Covered vehicular passageways, except for roof assemblies of heavy timber construction in the passageways | 25 | 25 Vertical service spaces | 25 | 25 Notes to Table 3.1.13.2.: (1) See Articles 3.1.13.8. and 3.1.13.10.
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OBC Div. B 3.1.13.2. Flame-Spread Rating
(1)Except as otherwise required or permitted by this Subsection, the flame-spread rating of interior wall and ceiling finishes, including glazing and skylights, shall be not more than 150 and shall conform to Table 3.1.13.2.
(2)Except as permitted by Sentence (3), doors, other than those in Group A, Division 1 occupancies, need not conform to Sentence (1) provided they have a flame-spread rating not more than 200. (See Note A-3.1.13.2.(2))
(3)Doors within a dwelling unit need not conform to Sentences (1) and (2).
(4)Up to 10% of the total wall area and 10% of the total ceiling area of a wall or ceiling finish that is required by Sentence (1) to have a flame-spread rating less than 150 is permitted to have a flame-spread rating not more than 150, except that up to 25% of the total wall area of lobbies described in Sentence 3.4.4.2.(2) is permitted to have a flame-spread rating not more than 150.
(5)Except in the case of Group A, Division 1 occupancies, combustible doors, skylights, glazing and light diffusers and lenses shall not be considered in the calculation of wall and ceiling areas described in Sentence (4).
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OBC Div. B 3.1.13.6. Corridors
(1)Except as permitted by Sentences (2) and (3), the flame-spread rating shall be not more than 75 for the interior wall finish of
(a)a public corridor,
(b)a corridor used by the public in,
(i)an assembly occupancy, or
(ii)a care, care and treatment or detention occupancy,
(c)a corridor serving classrooms, or
(d)a corridor serving sleeping rooms in a care, care and treatment or detention occupancy.
(2)The flame-spread rating for corridors specified in Sentence (1) is permitted to be waived, provided the flame-spread rating is not more than
(a)25 on the upper half of the wall, and
(b)150 on the lower half of the wall.
(3)Where the floor area is sprinklered throughout, the flame-spread ratings for corridors specified in Sentences (1) and (2) shall be not more than 150.
(4)The flame-spread ratings specified in Sentences (1), (2) and (3) apply to occupancies in the corridor as well as to the corridor itself.
(5)Except as provided in Sentence (6), the interior ceiling finish of corridors and occupancies referred to in Sentences (1) and (4) shall have a flame-spread rating not more than 25.
(6)Where the floor area is sprinklered throughout, the flame-spread rating of the interior ceiling finish of corridors and occupancies referred to in Sentences (1) and (4) shall be not more than 150.
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OBC Div. B 3.1.15.2. Roof Coverings
(1)Except as provided by Sentences (2) to (4), every roof covering shall have a Class A, B or C classification as determined in accordance with Article 3.1.15.1.
(2)A roof covering is not required to have a Class A, B or C classification for
(a)a tent,
(b)an air-supported structure,
(c)a building of Group A, Division 2 occupancy not more than 2 storeys in building height and not more than 1,000 m² in building area, provided the roof covering is underlaid with noncombustible material, or
(d)a steel building system described in Article 4.3.4.3., provided the roof covering consists of brick, masonry, concrete, metal sheets or metal shingles.
(3)Except as provided in Sentence (5), roof coverings on buildings conforming to Article 3.2.2.51. or 3.2.2.60. shall have a Class A classification where the roof height is greater than 25 m measured from the floor of the first storey to the highest point of the roof.
(4)Except as provided in Sentence (5), roof coverings in buildings or parts of buildings permitted to be of encapsulated mass timber construction shall have a Class A classification if the roof height is greater than 25 m measured from the floor of the first storey to the highest point of the roof.
(5)Where buildings or parts thereof conforming to Article 3.2.2.48., 3.2.2.51., 3.2.2.57., 3.2.2.60. or 3.2.2.93. include non-contiguous roof assemblies at different elevations, the roof coverings referred to in Sentences (3) and (4) are permitted to be evaluated separately to determine the roof covering classification required.
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OBC Div. B 3.1.16.1. Fabric Awnings, Canopies and Marquees
(1)Fabrics used as part of an awning, canopy or marquee that is located within or attached to a building of any type of construction shall conform to CAN/ULC-S109, "Standard Method of Flame Tests of Flame-Resistant Fabrics and Films."
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OBC Div. B 3.1.17.2. Public Pools
(1)The occupant load of a public pool, except a wave action pool, shall be determined by the following formula:
occupant load = D/2.5 + S/1.4
where.
D = the water surface area in square metres of the part of the pool that is deeper than 1,350 mm; and
S = the water surface area in square metres of the part of the pool that is 1,350 mm in depth or less.
(2)The occupant load of a wave action pool shall be determined by the following formula:
occupant load = D/2.5 + S/1.1
where,
D = the water surface area in square metres of the part of the pool where the still water depth is greater than 1,000 mm; and
S = the water surface area in square metres of the part of the pool where the still water depth is 1,000 mm or less
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OBC Div. B 3.1.19.1. Drainage
(1)The building shall be located and the building site graded so that water will not accumulate at or near the building and will not adversely affect any adjacent properties.
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OBC Div. B 3.1.20.1. Clearance to Buildings
(1)A building shall not be located beneath existing above ground electrical conductors.
(2)The horizontal clearance measured from the maximum conductor swing to the building, including balconies, fire escapes, flat roofs or other accessible projections beyond the face of the building, shall,
(a)be not less than 1 m, for electrical conductors carrying voltages 750 V or less, except where necessary to connect to the electrical wiring of the building,
(b)be not less than 3 m, for electrical conductors carrying voltages greater than 750 V but not exceeding 46 kV,
(c)be not less than 3.7 m, for electrical conductors carrying voltages greater than 46 kV but not exceeding 69 kV, or
(d)conform to the requirements of CAN/CSA-C22.3 No.1, "Overhead Systems," for electrical conductors carrying voltages greater than 69 kV.
(3)Where the swing of an above ground electrical conductor not owned or operated by an electrical supply authority is not known, a swing of not less than 1.8 m shall be used.
(4)Sentences (1) to (3) do not apply to a building containing electrical equipment and electrical installations used exclusively in the generation, transformation or transmission of electrical power or energy intended for sale or distribution to the public.
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OBC Div. B 3.1.21.1. Glass
(1)Except as provided in Sentence 3.3.4.7.(2), glass in guards shall conform to MMAH Supplementary Standard SB-13, "Glass in Guards."
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