Building size and construction relative to occupancy (3.2.1, 3.2.2) (Complex Buildings)

Last updated October 22, 2026

Values this chapter turns on

max height, sprinklered combustible Group D: 6 storeys; max height, sprinklered combustible Group D
max mezzanine area, as a share of the open room: 40%; max mezzanine area, as a share of the open room
perimeter distance to a street for streets faced: 15 m; perimeter distance to a street for streets faced
max occupant load of an impeded egress zone: 100 persons; max occupant load of an impeded egress zone

Subsection 3.2.2. decides how a building must be built. You pick one construction article (3.2.2.20. to 3.2.2.93.) that matches the major occupancy, building height, building area, number of streets faced and sprinklering. That article then sets the construction type and the fire-resistance ratings of floors, roofs, mezzanines and their supports. Subsection 3.2.1. settles how height and area are counted.

General: building height exceptions, storage garages and floor assemblies

3.2.1.1. lists what does not count as a storey:

A rooftop enclosure used only for elevator machinery, a stairway or a service room.
Space under arena seating used only for dressing rooms, concessions and similar uses.
The space above a mezzanine, if mezzanines total no more than 40% of the open area of the room and the space above stays open. Partitions over 1,070 mm are not allowed, though one enclosed space of up to 10% may be. Otherwise mezzanines are capped at 10% of the floor area, and 10% of a suite.
Each mezzanine level stacked above the first mezzanine counts as a storey.

A basement storage garage may be treated as a separate building if the floor and roof over it and its above-grade walls are 2 h noncombustible fire separations (3.2.1.2.). Unprotected openings in its walls are then allowed only if the garage is sprinklered and protected by a 1 m or 2 m projection or setback.

The floor over a basement is a fire separation rated as the construction article requires, but never less than 45 min (3.2.1.4.). Where the building need not be sprinklered, each basement is either sprinklered or split into fire compartments of 600 m² or less (3.2.1.5.).

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Application, streets, multiple occupancies and roof occupancies

Several major occupancies. The height and area of the whole building are used for every occupancy (3.2.2.5.). Normally the most restricted occupancy governs the whole building (3.2.2.6.). Where one occupancy sits entirely above another, each portion is designed as if the whole building were that occupancy. The floor between them is rated for the lower occupancy (3.2.2.7.). An occupancy group totalling no more than 10% of the storey's floor area is ignored for 3.2.2., unless it is Group F, Division 1 or 2 (3.2.2.8.). A retirement home is always treated as a separate major occupancy (3.2.2.4.).

Streets. Every building faces a street, and an access route meeting 3.2.5. counts as a street (3.2.2.10.):

Perimeter within 15 m of a street	Streets faced
at least 50%	2
at least 75%	3

Tunnels, bridges and enclosed spaces never count as streets. A roof that supports an occupancy is built like a floor assembly (3.2.2.13.).

Deep basements. If any part of a building goes more than one storey below ground, the basements are sprinklered. The floors below ground are 3 h fire separations for Group E or F, Division 1 or 2, and 2 h for other uses (3.2.2.15.).

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Automatic sprinkler requirements

3.2.2.18. lists every construction article whose title says "Sprinklered". Choosing one of those articles means sprinklering throughout. Sprinklers required on any storey must also go in all lower storeys, even where the article would have let those storeys go without.

A building with an impeded egress zone can avoid the Group B, Division 1 articles if it meets 3.2.2.19.:

sprinklered and 1 storey;
no contained use area, sleeping accommodation, high-hazard industrial or mercantile use;
the zone stays within its fire compartment and holds 100 people or fewer.

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Construction articles by Group (A to F)

Every Group and Division except Group A, Division 4 and Group F, Division 1 has an "any height, any area, sprinklered" article. Each one requires noncombustible construction, 2 h floors, 1 h mezzanines and supports matching what they carry. Examples: 3.2.2.20. for Group A, Division 1, 3.2.2.36. for detention, 3.2.2.38. for care and treatment and 3.2.2.42. for care. Smaller buildings get relief.

Group B article	Height	Building area	Construction	Floors
B-1, 3.2.2.37.	up to 3 storeys	unlimited at 1 storey, 12,000 m² at 2, 8,000 m² at 3	noncombustible	1 h
B-2, 3.2.2.39.	up to 3 storeys	same as above	noncombustible	1 h
B-2, 3.2.2.40.	up to 2 storeys	2,400 m² at 1, 1,600 m² at 2	combustible permitted	45 min
B-2, 3.2.2.41.	1 storey	500 m²	combustible permitted	n/a
B-3, 3.2.2.44.	up to 3 storeys	5,400 / 2,700 / 1,800 m²	combustible permitted	1 h
B-3, 3.2.2.46.	1 storey	600 m²	combustible permitted	n/a

Every Group B article is a sprinklered article. Other Groups also have articles for smaller buildings, some unsprinklered with areas that depend on streets faced:

Group C noncombustible, up to 4 storeys (3.2.2.50.): 1 h floors and roof. At 3 storeys the limit is 4,000 m² facing one street, rising with more streets. The 4th storey is allowed only where no more than one dwelling unit sits above another.
Group D sprinklered combustible, up to 6 storeys (3.2.2.60.): at most 18 m from the first floor to the top floor level. Areas run from 18,000 m² at 1 storey down to 3,000 m² at 6. Floors and roof are 1 h, and a roof more than 25 m up is noncombustible or fire-retardant-treated wood.
Group E up to 2 storeys (3.2.2.70.) and Group F, Division 2 up to 2 storeys (3.2.2.80.): combustible permitted, 45 min floors. Areas are 1,000 m² at 1 storey on one street and 600 m² at 2 storeys.

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Common traps

Using the area of one occupancy instead of the whole building to pick an article.
Rating the floor between superimposed occupancies for the upper one. It is the lower one.
Forgetting that sprinklers on an upper storey force sprinklers below.
Treating a basement floor as unrated because the article allows no rating. 3.2.1.4. sets a 45 min floor.
Missing that all Group B articles are sprinklered and most need noncombustible construction.

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
General: building height exceptions, storage garages and floor assemblies	A basement storage garage may be treated as a separate building if the floor and roof over it and its above-grade walls are 2 h noncombustible fire separations.
Application, streets, multiple occupancies and roof occupancies	Tunnels, bridges and enclosed spaces never count as streets.
Construction articles by Group (A to F)	Every Group and Division except Group A, Division 4 and Group F, Division 1 has an "any height, any area, sprinklered" article.

General: building height exceptions, storage garages and floor assemblies
A basement storage garage may be treated as a separate building if the floor and roof over it and its above-grade walls are 2 h noncombustible fire separations.
Application, streets, multiple occupancies and roof occupancies
Tunnels, bridges and enclosed spaces never count as streets.
Construction articles by Group (A to F)
Every Group and Division except Group A, Division 4 and Group F, Division 1 has an "any height, any area, sprinklered" article.

Usual exam traps

Using the area of one occupancy instead of the whole building to pick an article.
Rating the floor between superimposed occupancies for the upper one. It is the lower one.
Forgetting that sprinklers on an upper storey force sprinklers below.
Treating a basement floor as unrated because the article allows no rating. 3.2.1.4. sets a 45 min floor.
Missing that all Group B articles are sprinklered and most need noncombustible construction.

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Questions on Building size and construction relative to occupancy (3.2.1, 3.2.2), in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

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Code cited in this chapter

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

OBC Div. B 3.2.1.1. Exceptions in Determining Building Height
(1)A rooftop enclosure provided for elevator machinery, a stairway or a service room used for no purpose other than for service to the building, shall not be considered as a storey in calculating the building height.
(2)Space under tiers of seats in a building of the arena type shall not be considered as adding to the building height provided the space is used only for dressing rooms, concession stands and similar purposes incidental to the major occupancy of the building.
(3)Except as required by Sentence (5), the space above a mezzanine need not be considered as a storey in calculating building height provided
(a)the aggregate area of mezzanines that are not superimposed does not exceed 40% of the open area of the room in which they are located, and (See Note A-3.2.1.1.(3)(a))
(b)except as permitted in Sentences (7) and 3.3.2.13.(3) the space above the mezzanine is used as an open area without partitions or subdividing walls higher than 1,070 mm above the mezzanine floor.
(4)Except as required by Sentence (5), the space above a mezzanine need not be considered as a storey in calculating the building height provided
(a)the aggregate area of mezzanines that are not superimposed and do not meet the conditions of Sentence (3) does not exceed 10% of the floor area in which they are located, and
(b)the area of a mezzanine in a suite does not exceed 10% of the area of that suite.
(5)Except as permitted by Sentence (6), each level of mezzanine that is partly or wholly superimposed above the first level of mezzanine shall be considered as a storey in calculating the building height.
(6)Platforms intended solely for periodic inspection and elevated maintenance catwalks need not be considered as floor assemblies or mezzanines for the purpose of calculating building height, provided
(a)they are not used for storage, and
(b)they are constructed with noncombustible materials unless the building is permitted to be of combustible construction.
(7)The space above a mezzanine conforming to Sentence (3) is permitted to include an enclosed space whose area does not exceed 10% of the open area of the room in which the mezzanine is located, provided the enclosed space does not obstruct visual communication between the open space above the mezzanine and the room in which it is located. (See Note A-3.2.1.1.(3)(a)
(8)A service space in which facilities are included to permit a person to enter and to undertake maintenance and other operations pertaining to building services from within the service space need not be considered a storey if it conforms to Articles 3.2.5.14. and 3.3.1.25., and Sentences 3.2.4.18.(11), 3.2.7.3.(2), 3.3.1.3.(7), 3.4.2.4.(3) and 3.4.4.4.(9). (See Note A-3.2.1.1.(8))
Open OBC Div. B 3.2.1.1. in the code viewer
OBC Div. B 3.2.1.2. Storage Garage Considered as a Separate Building
(1)A basement used primarily as a storage garage is permitted to be considered as a separate building for the purposes of Subsection 3.2.2. and Sentences 3.2.5.12.(2) and (3), provided the floor and roof assemblies above the basement and the exterior walls of the basement above the adjoining ground level are constructed as fire separations of noncombustible construction having a fire-resistance rating not less than 2 h and protected in conformance with Clause 3.1.10.2.(4)(a), except as permitted by Sentence (2). (See Notes A-3.1.10.2.(4) and A-3.2.5.12(2))
(2)The exterior wall of a basement that is required to be a fire separation with a fire-resistance rating in accordance with Sentence (1) is permitted to be penetrated by openings that are not protected by closures provided
(a)the storage garage is sprinklered throughout,
(b)every opening in the exterior wall is separated from storeys above the opening by a projection of the floor or roof assembly above the basement, extending not less than
(i)1 m beyond the exterior face of the storage garage if the upper storeys are required to be of noncombustible construction, or
(ii)2 m beyond the exterior face of the storage garage if the upper storeys are permitted to be of combustible construction or encapsulated mass timber construction, or
(c)the exterior walls of any storeys located above the floor or roof assembly referred to in Sentence (1) are recessed behind the outer edge of the assembly by not less than
(i)1 m if the upper storeys are required to be of noncombustible construction, or
(ii)2 m if the upper storeys are permitted to be of combustible construction or encapsulated mass timber construction.
(3)The floor or roof assembly projection referred to in Clause (2)(b) shall have a fire-resistance rating not less than 2 h and shall have no openings within the projection.
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OBC Div. B 3.2.1.4. Floor Assembly Over Basement
(1)Except as permitted by Sentence 3.2.2.47.(3), 3.2.2.49.(3), 3.2.2.50.(3), 3.2.2.52.(3), 3.2.2.53.(3), 3.2.2.54.(3), 3.2.2.55.(3) or 3.2.2.93.(3), a floor assembly immediately above a basement shall be constructed as a fire separation having a fire-resistance rating conforming to the requirements of Articles 3.2.2.20. to 3.2.2.93. for a floor assembly, but not less than 45 min
(2)All loadbearing walls, columns and arches supporting a floor assembly immediately above a basement shall have a fire-resistance rating not less than that required by Sentence (1) for the floor assembly.
Open OBC Div. B 3.2.1.4. in the code viewer
OBC Div. B 3.2.1.5. Fire Containment in Basements
(1)Except as permitted by Sentences (2) and 3.2.2.15.(3), in a building in which an automatic sprinkler system is not required to be installed by Articles 3.2.2.18., every basement shall
(a)be sprinklered throughout, or
(b)be subdivided into fire compartments not more than 600 m² in area by a fire separation having a fire-resistance rating not less than that required for the floor assembly immediately above the basement.
(2)An open-air storey need not conform to Sentence (1).
Open OBC Div. B 3.2.1.5. in the code viewer
OBC Div. B 3.2.2.5. Applicable Building Height and Area
(1)In determining the fire safety requirements of a building in relation to each of the major occupancies contained therein, the building height and building area of the entire building shall be used.
(2)For the purposes of Sentence (1), a retirement home is deemed to be a separate major occupancy.
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OBC Div. B 3.2.2.6. Multiple Major Occupancies
(1)Except as permitted by Articles 3.2.2.7. and 3.2.2.8., and Sentences 3.2.2.48.(4), 3.2.2.51.(5), 3.2.2.57.(3) and 3.2.2.60.(4) and 3.2.2.93.(5) to (7), in a building containing more than one major occupancy, the requirements of this Subsection for the most restricted major occupancy contained shall apply to the whole building.
(2)For the purposes of Sentence (1), a retirement home is deemed to be a separate major occupancy.
(3)In a building or part thereof constructed in conformance with Article 3.2.2.48., 3.2.2.57. or 3.2.2.93. containing more than one major occupancy, the most restrictive encapsulation requirements of Article 3.1.6.4. and Table 3.2.2.93. for any major occupancy contained within a storey shall apply to the encapsulation required on the interior of a public corridor or exit within that storey.
Open OBC Div. B 3.2.2.6. in the code viewer
OBC Div. B 3.2.2.7. Superimposed Major Occupancies
(1)Except as permitted in Article 3.2.2.8. and Sentences 3.2.2.18.(2), 3.2.2.48.(4), 3.2.2.51.(5), 3.2.2.57.(3), 3.2.2.60.(4) and 3.2.2.93.(5) to (7), in a building in which one major occupancy is located entirely above another major occupancy, the requirements in this Subsection for each portion of the building containing a major occupancy shall apply to that portion as if the entire building were of that major occupancy.
(2)If one major occupancy is located above another major occupancy, the fire-resistance rating of the floor assembly between the major occupancies shall be determined on the basis of the requirements of this Subsection for the lower major occupancy. (See also Article 3.1.3.1.)
(3)For the purposes of Sentences (1) and (2), a retirement home is deemed to be a separate major occupancy.
(4)In a building or part thereof constructed in conformance with Article 3.2.2.48., 3.2.2.57. or 3.2.2.93., if one major occupancy is located above another major occupancy,
(a)the most restrictive encapsulation requirements of Article 3.1.6.4. and Table 3.2.2.93. for any major occupancy contained within the building shall apply to the encapsulation required on the interior of vertical service spaces and exit stairs, and
(b)the encapsulation requirements of Article 3.1.6.4. and Table 3.2.2.93. for a mass timber floor assembly between the major occupancies shall be determined on the basis of the requirements for,
(i)the upper major occupancy for the encapsulation of the upper surface of the mass timber floor assembly, and
(ii)the lower major occupancy for the encapsulation of the underside of the mass timber floor assembly.
Open OBC Div. B 3.2.2.7. in the code viewer
OBC Div. B 3.2.2.8. Exceptions for Major Occupancies
(1)In a building in which the aggregate area of all major occupancies in a particular Group or Division is not more than 10% of the floor area of the storey in which they are located, these major occupancies need not be considered as major occupancies for the purposes of this Subsection, provided they are not classified as Group F, Division 1 or 2 occupancies.
(2)For the purposes of Sentence (1), a retirement home is deemed to be a separate major occupancy.
(3)A helicopter landing area on the roof of a building need not be considered a major occupancy for purposes of Subsection 3.2.2. where such landing area is not more than 10% of the area of the roof.
Open OBC Div. B 3.2.2.8. in the code viewer

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OBC Div. B 3.2.2.4. Buildings with Multiple Major Occupancies
(1)The requirements restricting fire spread and collapse for a building of a single major occupancy classification are provided in this Subsection according to its building height and building area.
(2)If a building contains more than one major occupancy, classified in more than one Group or Division, the requirements of this Subsection concerning building size and construction relative to major occupancy shall apply according to Articles 3.2.2.5. to 3.2.2.8.
(3)For the purposes of Sentences (1) and (2), a retirement home is deemed to be a separate major occupancy.
Open OBC Div. B 3.2.2.4. in the code viewer
OBC Div. B 3.2.2.10. Streets
(1)Every building shall face a street located in conformance with the requirements of Articles 3.2.5.4 and 3.2.5.5 for access routes.
(2)For the purposes of Subsections 3.2.2. and 3.2.5. an access route conforming to Subsection 3.2.5. is permitted to be considered as a street.
(3)A building conforming to Article 3.2.2.51. or 3.2.2.60. is considered to face one street, where
(a)not less than 25% of the building perimeter is located within 15 m of a street or streets, or
(b)not less than 10% of the building perimeter is located within 15 m of a street or streets, provided the exterior cladding conforms to Sentence 3.1.4.8.(2).
(4)A building is considered to face 2 streets provided not less than 50% of the building perimeter is located within 15 m of the street or streets.
(5)A building is considered to face 3 streets provided not less than 75% of the building perimeter is located within 15 m of the street or streets.
(6)Enclosed spaces, tunnels, bridges and similar structures, even though used for vehicular or pedestrian traffic, are not considered as streets for the purpose of this Part.
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OBC Div. B 3.2.2.13. Occupancy on Roof
(1)A portion of a roof that supports an occupancy shall be constructed in conformance with the fire separation requirements of Articles 3.2.2.20. to 3.2.2.93. for floor assemblies.
Open OBC Div. B 3.2.2.13. in the code viewer
OBC Div. B 3.2.2.15. Storeys Below Ground
(1)If a building is erected entirely below the adjoining finished ground level and does not extend more than one storey below that ground level, the minimum precautions against fire spread and collapse shall be the same as are required for basements under a building of 1 storey in building height having the same occupancy and building area.
(2)If any portion of a building is erected entirely below the adjoining finished ground level and extends more than 1 storey below that ground level, the following minimum precautions against fire spread and collapse shall be taken:
(a)except as permitted by Sentence (3), the basements shall be sprinklered throughout,
(b)a floor assembly below the ground level shall be constructed as a fire separation with a fire-resistance rating not less than
(i)3 h if the basements are used as Group E or Group F, Division 1 or 2 occupancies, or
(ii)2 h if the basements are not used as Group E or Group F, Division 1 or 2 occupancies, and
(c)all loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the construction that they support.
(3)If the first storey of a building is not required to be sprinklered, sprinklers are not required in the storey immediately below the first storey, provided the storey below
(a)contains only residential occupancies, and
(b)has at least one unobstructed access opening conforming to Sentence 3.2.5.1.(2) installed on that storey for each 15 m of wall length in at least one wall required by this Subsection to face a street.
Open OBC Div. B 3.2.2.15. in the code viewer
OBC Div. B 3.2.2.18. Automatic Sprinkler System Required
(1)Except as permitted by Sentence (2), an automatic sprinkler system conforming to the requirements of Articles 3.2.4.7., 3.2.4.8., 3.2.4.9. and 3.2.5.12. shall be installed throughout a building regulated by one or more of Articles 3.2.2.20., 3.2.2.21., 3.2.2.22., 3.2.2.23., 3.2.2.24., 3.2.2.26., 3.2.2.27., 3.2.2.29., 3.2.2.31., 3.2.2.33., 3.2.2.36., 3.2.2.37., 3.2.2.38., 3.2.2.39., 3.2.2.40., 3.2.2.41., 3.2.2.42., 3.2.2.43., 3.2.2.44., 3.2.2.45., 3.2.2.46., 3.2.2.47., 3.2.2.48., 3.2.2.49., 3.2.2.51., 3.2.2.52., 3.2.2.55., 3.2.2.55A., 3.2.2.55B., 3.2.2.55C., 3.2.2.55D., 3.2.2.55.E., 3.2.2.56., 3.2.2.57., 3.2.2.59., 3.2.2.60., 3.2.2.61., 3.2.2.63., 3.2.2.65., 3.2.2.66., 3.2.2.67., 3.2.2.69., 3.2.2.71., 3.2.2.72., 3.2.2.73., 3.2.2.74., 3.2.2.76., 3.2.2.77., 3.2.2.79., 3.2.2.81., 3.2.2.82., 3.2.2.84., 3.2.2.86., 3.2.2.88., 3.2.2.90. and 3.2.2.93.
(2)If a storey in a building or a floor area is required to have an automatic sprinkler system installed throughout in accordance with one or more of Articles 3.2.2.20. to 3.2.2.93. or Section 3.3., the automatic sprinkler system shall also be installed throughout all lower storeys in the building notwithstanding permission in Articles 3.2.2.20. to 3.2.2.93. to construct one or more of those storeys without installing automatic sprinkler protection. (See Note A-3.2.2.18.(2))
Open OBC Div. B 3.2.2.18. in the code viewer
OBC Div. B 3.2.2.19. Buildings Containing Impeded Egress Zones
(1)A building containing an impeded egress zone and conforming to the appropriate requirements of Articles 3.2.2.20. to 3.2.2.93. is not required to conform to the requirements of Articles 3.2.2.36. and 3.2.2.37. for a Group B, Division 1 major occupancy provided
(a)the building is sprinklered throughout,
(b)it is not more than 1 storey in building height,
(c)it does not include
(i)a contained use area,
(ii)sleeping accommodation,
(iii)a high-hazard industrial occupancy, or
(iv)a mercantile occupancy,
(d)the building area is not more than 6,400 m² if the building includes a medium-hazard industrial occupancy,
(e)the impeded egress zone does not extend beyond the boundaries of the fire compartment in which it is located, and
(f)the occupant load of the impeded egress zone is not more than 100.
Open OBC Div. B 3.2.2.19. in the code viewer
OBC Div. B 3.2.2.20. Group A, Division 1, Any Height, Any Area, Sprinklered
(1)Except as permitted by Articles 3.2.2.21. and 3.2.2.22., a building classified as Group A, Division 1 shall conform to Sentence (2).
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building shall be sprinklered throughout,
(b)floor assemblies shall be fire separations with a fire-resistance rating not less than 2 h,
(c)mezzanines shall have a fire-resistance rating not less than 1 h, and
(d)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.36. Group B, Division 1, Any Height, Any Area, Sprinklered
(1)Except as permitted by Article 3.2.2.37., a building classified as Group B, Division 1 shall conform to Sentence (2).
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building shall be sprinklered throughout,
(b)floor assemblies shall be fire separations with a fire-resistance rating not less than 2 h,
(c)mezzanines shall have a fire-resistance rating not less 1 h, and
(d)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.38. Group B, Division 2, Any Height, Any Area, Sprinklered
(1)Except as permitted by Articles 3.2.2.39. to 3.2.2.41., a building classified as Group B, Division 2 shall conform to Sentence (2).
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building shall be sprinklered throughout,
(b)floor assemblies shall be fire separations with a fire-resistance rating not less than 2 h,
(c)mezzanines shall have a fire-resistance rating not less 1 h, and
(d)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
Open OBC Div. B 3.2.2.38. in the code viewer
OBC Div. B 3.2.2.42. Group B, Division 3, Any Height, Any Area, Sprinklered
(1)Except as permitted by Articles 3.2.2.43. to 3.2.2.46. and 3.2.2.93., a building classified as Group B, Division 3 shall conform to Sentence (2).
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building shall be sprinklered throughout,
(b)floor assemblies shall be fire separations with a fire-resistance rating not less than 2 h,
(c)mezzanines shall have a fire-resistance rating not less than 1 h, and
(d)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
Open OBC Div. B 3.2.2.42. in the code viewer
OBC Div. B 3.2.2.37. Group B, Division 1, up to 3 Storeys, Sprinklered
(1)A building classified as Group B, Division 1 is permitted to conform to Sentence (2) provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 3 storeys in building height, and
(c)it has a building area
(i)that is not limited if the building is not more than 1 storey in building height,
(ii)not more than 12,000 m² if 2 storeys in building height, or
(iii)not more than 8,000 m² if 3 storeys in building height.
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 1 h,
(b)mezzanines shall have a fire-resistance rating not less than 1 h, and
(c)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.39. Group B, Division 2, up to 3 Storeys, Sprinklered
(1)A building classified as Group B, Division 2 is permitted to conform to Sentence (2) provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 3 storeys in building height, and
(c)it has a building area,
(i)that is not limited if the building is not more than 1 storey in building height,
(ii)not more than 12,000 m² if 2 storeys in building height, or
(iii)not more than 8,000 m² if 3 storeys in building height.
(2)Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 1 h,
(b)mezzanines shall have a fire-resistance rating not less than 1 h, and
(c)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.40. Group B, Division 2, up to 2 Storeys, Sprinklered
(1)A building classified as Group B, Division 2 is permitted to conform to Sentence (2) provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 2 storeys in building height, and
(c)it has a building area not more than
(i)2,400 m² if 1 storey in building height, or
(ii)1,600 m² if 2 storeys in building height.
(2)The building referred to in Sentence (1) is permitted to be of combustible construction or noncombustible construction used singly or in combination, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 45 min,
(b)mezzanines shall have, if of combustible construction, a fire-resistance rating not less than 45 min, and
(c)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.41. Group B, Division 2, One Storey, Sprinklered
(1)A building classified as Group B, Division 2 is permitted to be of combustible construction or noncombustible construction used singly or in combination, provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 1 storey in building height, and
(c)it has a building area not more than 500 m².
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OBC Div. B 3.2.2.44. Group B, Division 3, Up to 3 Storeys, Sprinklered
(1)A building classified as Group B, Division 3 is permitted to conform to Sentence (2) provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 3 storeys in building height, and
(c)it has a building area not more than
(i)5,400 m² if 1 storey in building height,
(ii)2,700 m² if 2 storeys in building height, or
(iii)1,800 m² if 3 storeys in building height.
(2)The building referred to in Sentence (1) is permitted to be of combustible construction or noncombustible construction used singly or in combination, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 1 h,
(b)mezzanines shall have a fire-resistance rating not less than 1 h, and
(c)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.46. Group B, Division 3, One Storey, Sprinklered
(1)A building classified as Group B, Division 3 is permitted to be of combustible construction or noncombustible construction, used singly or in combination, provided
(a)except as permitted by Sentences 3.2.2.7.(1) and 3.2.2.18.(2), the building is sprinklered throughout,
(b)it is not more than 1 storey in building height, and
(c)it has a building area not more than 600 m².
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OBC Div. B 3.2.2.50. Group C, up to 4 Storeys, Noncombustible Construction
(1)A building classified as Group C, other than a retirement home, is permitted to conform to Sentence (2) provided
(a)it is not more than
(i)3 storeys in building height, or
(ii)4 storeys in building height provided there is not more than one dwelling unit above another dwelling unit, and vertical fire separations of adjacent dwelling units conform to Sentence (4), and
(b)it has a building area not more than the value in Table 3.2.2.50.
(2)The building referred to in Sentence (1) shall be of noncombustible construction, and
(a)except as permitted by Sentence (3), floor assemblies shall be fire separations with a fire-resistance rating not less than 1 h,
(b)mezzanines shall have a fire-resistance rating not less than 1 h,
(c)roof assemblies shall have a fire-resistance rating not less than 1 h, and
(d)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
(3)In a building that contains dwelling units that have more than one storey, subject to the requirements of Sentence 3.3.4.2.(3), the floor assemblies, including floors over basements, which are entirely contained within these dwelling units, shall have a fire-resistance rating not less than 1 h but need not be constructed as fire separations.
(4)The dwelling units described in Subclause (1)(a)(ii) shall be separated by continuous vertical fire separations that extend through all storeys and service spaces of the separated portions.
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OBC Div. B 3.2.2.60. Group D, up to 6 Storeys, Sprinklered
(1)A building classified as Group D is permitted to conform to Sentence (2) provided
(a)it is sprinklered throughout,
(b)it is not more than 6 storeys in building height,
(c)it has a height of not more than 18 m measured between the floor of the first storey and the uppermost floor level that does not serve a rooftop enclosure for elevator machinery, a stairway or a service room used only for service to the building, and
(d)it has a building area of not more than
(i)18,000 m² if 1 storey in building height,
(ii)9,000 m² if 2 storeys in building height,
(iii)6,000 m² if 3 storeys in building height,
(iv)4,500 m² if 4 storeys in building height,
(v)3,600 m² if 5 storeys in building height, or
(vi)3,000 m² if 6 storeys in building height.
(2)The building referred to in Sentence (1) is permitted to be of combustible construction or noncombustible construction used singly or in combination, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 1 h,
(b)roof assemblies shall have a fire-resistance rating not less than 1 h,
(c)except as provided by Sentence (3), where the roof assembly has a height greater than 25 m measured from the floor of the first storey to the highest point of the roof assembly, the roof assembly shall be constructed of noncombustible construction or fire-retardant-treated wood conforming to Article 3.1.4.5.,
(d)mezzanines shall have a fire-resistance rating not less than 1 h, and
(e)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
(3)Where buildings conforming to Sentence (2) include non-contiguous roof assemblies at different elevations, the roof assemblies are permitted to be evaluated separately to determine which ones are required to be constructed in accordance with Clause (2)(c).
(4)Group A, Division 2 major occupancies, Group E major occupancies, Group F, Division 2 and 3 major occupancies and storage garages located in a building or part thereof within the scope of this Article are permitted to be constructed in accordance with this Article, provided
(a)the Group A, Division 2 major occupancy, Group E major occupancy and Group F, Division 2 or 3 major occupancy are located below the third storey, and
(b)storage garages are located below the fourth storey. (See also Article 4.4.2.1.)(See Note A-3.2.2.51.(5) and 3.2.2.60.(4))
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OBC Div. B 3.2.2.70. Group E, up to 2 Storeys
(1)A building classified as Group E is permitted to conform to Sentence (2) provided
(a)it is not more than 2 storeys in building height, and
(b)it has a building area not more than the value in Table 3.2.2.70.
(2)The building referred to in Sentence (1) is permitted to be of combustible construction or noncombustible construction used singly or in combination, and
(a)floor assemblies shall be fire separations with a fire-resistance rating not less than 45 min, and
(b)loadbearing walls, columns and arches shall have a fire-resistance rating not less than that required for the supported assembly.
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OBC Div. B 3.2.2.80. Group F, Division 2, up to 2 Storeys
(1)A building classified as Group F, Division 2 is permitted to conform to Sentence (2) provided
(a)it is not more than 2 storeys in building height, and
(b)it has a building area not more than the value in Table 3.2.2.80.
(2)The building referred to in Sentence (1) is permitted to be of combustible construction or noncombustible construction used singly or in combination, and
(a)floor assemblies shall be fire separations and, if of combustible construction, shall have a fire-resistance rating not less than 45 min, and
(b)loadbearing walls, columns and arches supporting an assembly required to have a fire-resistance rating shall
(i)have a fire-resistance rating not less than 45 min, or
(ii)be of noncombustible construction.
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