Part 3 structural items: Building Structural Study Guide

Last updated October 22, 2026

Values this chapter turns on

firewall rating with Group E, F1 or F2 on a side: 4 h; firewall rating with Group E, F1 or F2 on a side
exterior stair guard height above 10 m: 1,500 mm; exterior stair guard height above 10 m
stretcher length one elevator must carry: 2,010 mm; stretcher length one elevator must carry
max area per unsprinklered self-storage zone: 500 m²; max area per unsprinklered self-storage zone

Part 3 is mostly fire and life safety, but many of its articles set structural minimums or send the design to Part 4. The Building Structural exam picks those out. Learn the numbers and the cross-references. Classification by major occupancy under OBC Div. B 3.1.2.1. drives several of them. A building with more than one major occupancy is classified by all of them.

Heavy timber and supporting construction

Heavy timber means solid masses with smooth surfaces and no thin sections or sharp projections OBC Div. B 3.1.4.7.. Minimum member sizes come from Table 3.1.4.7.. Read it by what the member supports (roof only, or floors), then by element type:

Element	Roofs only (solid sawn)	Floors (solid sawn)
Columns	140 x 191 mm	191 x 191 mm
Beams, girders, trusses	89 x 140 mm	140 x 241 or 191 x 191 mm

Glued-laminated and round sizes sit in the next columns. Picking them by mistake is a common error.

Heavy timber floors and roofs have their own minimums:

Floors: plank at least 64 mm thick, splined or tongued and grooved, or 38 x 89 mm on edge. Cover with 19 mm flooring or 12.5 mm panels, and keep 15 mm clear of walls for expansion.
Roofs: 38 mm plank, or 28 mm phenolic-bonded panels.
Columns: continuous or superimposed through all storeys, with proper caps or splice connections.

Supporting construction. Loadbearing walls, columns and arches under a rated floor or roof need at least the same rating. Supports of a service room are the exception OBC Div. B 3.1.7.5.. A noncombustible rated assembly must be supported by noncombustible construction, with limited exceptions for encapsulated mass timber.

Combustible framing that bears on or abuts a noncombustible fire separation must be built so its collapse in a fire does not collapse the separation OBC Div. B 3.1.8.2.. In buildings required to be noncombustible, combustible stage flooring and short raised-platform sleepers (50 to 300 mm) are allowed OBC Div. B 3.1.5.10..

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Firewalls, glass in guards and structural fire protection

Firewall ratings OBC Div. B 3.1.10.2.:

4 h where either side has a Group E or Group F, Division 1 or 2 occupancy.
2 h otherwise.
The rating comes from masonry or concrete.

A firewall of 2 h or less may be built of other materials only if all of these are met:

it is protected against damage;
it performs at least like masonry in fire, against impact and against moisture;
it does not separate Group B, Division 1 or 2 occupancies;
its design conforms to Article 4.1.5.17, the firewall lateral load rule from chapter 3.

Glass in guards in Part 3 buildings follows SB-13 OBC Div. B 3.1.21.1..

Exceptions to structural fire protection OBC Div. B 3.2.2.3.:

Item	No fire protection needed when
Steel lintel, loadbearing wall	opening is 2 m wide or less
Steel lintel, non-loadbearing wall	opening is 3 m wide or less
Wider steel lintels	supported at 2 m or less by rated members
Exterior steel balconies, stairs, fire escapes, canopies	outside the exterior wall
Members outside the face of buildings of 4 storeys or less (A, B, C, D, F3)	at least 1 m from unprotected openings, or shielded

Structural members outside the building face and within 3 m of the property line (or the centre line of a street) must be protected from exterior fire. The protection is at least the interior requirement and never less than 1 h OBC Div. B 3.2.3.9..

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Guards, handrails and fire escapes

Guards are at least 1,070 mm high in Part 3 OBC Div. B 3.3.1.18.. They are required in these places:

around roofs with access for purposes other than maintenance;
at drops of more than 600 mm;
where the ground within 1.2 m slopes more steeply than 1 in 2.

Openings in required guards must stop a 100 mm sphere (200 mm in industrial occupancies). Members between 140 mm and 900 mm above the floor must not make the guard climbable.

Exit stair guards are 1,070 mm high. On exterior stairs and landings more than 10 m above the ground they are 1,500 mm OBC Div. B 3.4.6.6..

Handrails OBC Div. B 3.4.6.5.:

one handrail on stairs narrower than 1,100 mm; one on each side of wider stairs and of ramps;
height between 865 and 1,070 mm;
loads from 4.1.5.14.(7): 0.9 kN at any point, plus 0.7 kN/m outside dwelling units.

Fire escapes are metal or concrete OBC Div. B 3.4.7.2.. Wood is allowed only on combustible buildings. Even then, posts and brackets must be at least 89 mm and all other woodwork at least 38 mm in least dimension.

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Elevators, access ladders and electrical vaults

In buildings over 3 storeys with elevators, one elevator per served storey must take a stretcher 2,010 x 610 mm lying flat OBC Div. B 3.5.4.1..

The anchorage of a fixed roof access ladder is designed and installed to Supplementary Standard SB-8 OBC Div. B 3.6.1.6..

Electrical equipment vaults OBC Div. B 3.6.2.7.:

enclosed in solid masonry or concrete rated 3 h, or 2 h if fire extinguishing is provided;
indoor vault roofs and floors of reinforced concrete at least 150 mm thick (floors on excavation 100 mm);
walls, roof and floor anchored together against explosion;
a liquid-tight floor with sills at least 100 mm high.

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Signs, racks, self-storage and existing buildings

Each of these Part 3 sections sends structural design to Part 4:

Sign structures are designed to Part 4 OBC Div. B 3.15.3.1..
Shelf and rack storage systems: every structural component is designed to Part 4, including posts, beams, decks, walkways, connections, and the slabs and foundations that support them OBC Div. B 3.16.1.3..

Self-service storage. In a self-service storage building, the first storey must be sprinklered, or divided into areas of no more than 500 m² by masonry or reinforced concrete fire separations of at least 1 h OBC Div. B 3.10.2.3..

Existing buildings. Section 3.18 applies to listed changes of use, such as a change to a post-disaster building or to a retirement home. It also applies to adding storeys to a combustible building so that it exceeds 4 storeys OBC Div. B 3.18.1.1.. The structural side is then handled through Part 11 and compensating construction.

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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
Heavy timber and supporting construction	Heavy timber means solid masses with smooth surfaces and no thin sections or sharp projections.
Firewalls, glass in guards and structural fire protection	Glass in guards in Part 3 buildings follows SB-13.
Guards, handrails and fire escapes	Openings in required guards must stop a 100 mm sphere (200 mm in industrial occupancies).
Elevators, access ladders and electrical vaults	In buildings over 3 storeys with elevators, one elevator per served storey must take a stretcher 2,010 x 610 mm lying flat.
Signs, racks, self-storage and existing buildings	An unsprinklered first storey of 1,400 m² needs at least 1,400/500 = 2.8, so 3 compartments.

Heavy timber and supporting construction
Heavy timber means solid masses with smooth surfaces and no thin sections or sharp projections.
Firewalls, glass in guards and structural fire protection
Glass in guards in Part 3 buildings follows SB-13.
Guards, handrails and fire escapes
Openings in required guards must stop a 100 mm sphere (200 mm in industrial occupancies).
Elevators, access ladders and electrical vaults
In buildings over 3 storeys with elevators, one elevator per served storey must take a stretcher 2,010 x 610 mm lying flat.
Signs, racks, self-storage and existing buildings
An unsprinklered first storey of 1,400 m² needs at least 1,400/500 = 2.8, so 3 compartments.

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Questions on Part 3 structural items, 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 3.1.2.1. 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.
Open OBC Div. B 3.1.2.1. in the code viewer
OBC Div. B 3.1.4.7. Heavy Timber Construction
(1)Wood elements in heavy timber construction shall be arranged in heavy solid masses and with essentially smooth flat surfaces to avoid thin sections and sharp projections.
(2)Except as permitted by Sentences (3) to (6) and (12), the minimum dimensions of wood elements in heavy timber construction shall conform to Table 3.1.4.7.
(3)Where splice plates are used at splices of roof arches supported on the tops of walls or abutments, roof trusses, roof beams and roof girders in heavy timber construction, they shall be not less than 64 mm thick.
(4)Floors in heavy timber construction shall be of glued-laminated or solid sawn plank not less than
(a)64 mm thick, splined or tongued and grooved, or
(b)38 mm wide and 89 mm deep set on edge and well-spiked together.
(5)Floors in heavy timber construction shall be laid
(a)so that no continuous line of end joints will occur except at points of support, and covered with
(i)tongued and grooved flooring not less than 19 mm thick laid crosswise or diagonally, or
(ii)tongued and grooved phenolic-bonded plywood, strandboard or waferboard not less than 12.5 mm thick, and
(b)not closer than 15 mm to the walls to provide for expansion, with the gap covered at the top or bottom.
(6)Roofs in heavy timber construction shall be of tongued and grooved phenolic-bonded plywood, strandboard or waferboard not less than 28 mm thick, or glued-laminated or solid sawn plank that is
(a)not less than 38 mm thick, splined or tongued and grooved, or
(b)not less than 38 mm wide and 64 mm deep set on edge and laid so that no continuous line of end joints will occur except at the points of support.
(7)Wood columns in heavy timber construction shall be continuous or superimposed throughout all storeys.
(8)Superimposed wood columns in heavy timber construction shall be connected by
(a)reinforced concrete or metal caps with brackets,
(b)steel or iron caps with pintles and base plates, or
(c)timber splice plates fastened to the columns by metal connectors housed within the contact faces.
(9)Where beams and girders in heavy timber construction enter masonry, wall plates, boxes of the self-releasing type or hangers shall be used.
(10)Wood girders and beams in heavy timber construction shall be closely fitted to columns, and adjoining ends shall be connected by ties or caps to transfer horizontal loads across the joints.
(11)In heavy timber construction, intermediate wood beams used to support a floor shall be supported on top of the girders or on metal hangers into which the ends of the beams are closely fitted.
(12)Roof arches supported on the tops of walls or abutments, roof trusses, roof beams and roof girders in heavy timber construction are permitted to be not less than 64 mm wide provided
(a)where two or more spaced members are used, the intervening spaces are
(i)blocked solidly throughout, or
(ii)tightly closed by a continuous wood cover plate not less than 38 mm thick secured to the underside of the members, or
(b)the underneath of the roof deck or sheathing is sprinklered.
Open OBC Div. B 3.1.4.7. in the code viewer
OBC Div. B Table 3.1.4.7. Heavy Timber Dimensions
Table 3.1.4.7. Heavy Timber Dimensions Forming Part of Sentence 3.1.4.7.(2) Supported Assembly | Structural Element | Solid Sawn (width × depth), mm × mm | Glued-Laminated (width × depth), mm × mm | Round (diam), mm Roofs only | Columns | 140×191 | 130×190 | 180 Roofs only | Arches supported on the tops of walls or abutments | 89×140 | 80×152 | N/A Roofs only | Beams, girders and trusses | 89×140 | 80×152 | N/A Roofs only | Arches supported at or near the floor line | 140×140 | 130×152 | N/A Floors, floors plus roofs | Columns | 191×191 | 175×190 | 200 Floors, floors plus roofs | Beams, girders, trusses and arches | 140×241 or 191×191 | 130×228 or 175×190 | N/A
Open OBC Div. B Table 3.1.4.7. in the code viewer
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.
Open OBC Div. B 3.1.7.5. in the code viewer
OBC Div. B 3.1.8.2. Combustible Construction Support
(1)Combustible construction that abuts on or is supported by a noncombustible fire separation shall be constructed so that its collapse under fire conditions will not cause the collapse of the fire separation.
Open OBC Div. B 3.1.8.2. in the code viewer
OBC Div. B 3.1.5.10. Combustible Flooring Elements
(1)Combustible stage flooring supported on noncombustible structural members is permitted in a building required to be of noncombustible construction.
(2)Wood members more than 50 mm but not more than 300 mm high applied directly to or set into a noncombustible floor slab are permitted for the construction of a raised platform in a building required to be of noncombustible construction provided the concealed spaces created are divided into compartments by fire blocks in conformance with Sentence 3.1.11.3.(2).
(3)The floor system for the raised platform referred to in Sentence (2) is permitted to include combustible subfloor and combustible finished flooring.
(4)Combustible finished flooring is permitted in a building required to be of noncombustible construction.
Open OBC Div. B 3.1.5.10. in the code viewer
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))
Open OBC Div. B 3.1.10.2. in the code viewer
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."
Open OBC Div. B 3.1.21.1. in the code viewer

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OBC Div. B 3.2.2.3. Exceptions to Structural Fire Protection
(1)Fire protection is not required for
(a)steel lintels above openings not more than 2 m wide in loadbearing walls and not more than 3 m wide in non-loadbearing walls.
(b)steel lintels above openings more than 2 m wide in loadbearing walls and more than 3 m wide in non-loadbearing walls provided the lintels are supported at intervals of not more than 2 m by structural members with the required fire-resistance rating,
(c)the bottom flanges of shelf angles and plates that are not a part of the structural frame,
(d)steel members for framework around elevator hoistway doorways, steel for the support of elevator and dumbwaiter guides, counterweights and other similar equipment, that are entirely enclosed in a hoistway and are not a part of the structural frame of the building,
(e)steel members of stairways and escalators that are not a part of the structural frame of a building,
(f)steel members of porches, exterior balconies, exterior stairways, fire escapes, cornices, marquees and other similar appurtenances, provided they are outside an exterior wall of a building, and
(g)loadbearing steel or concrete members wholly or partly outside a building face in a building not more than 4 storeys in building height and classified as Group A, B, C, D or F, Division 3 major occupancy provided the members are
(i)not less than 1 m away from any unprotected opening in an exterior wall, or
(ii)shielded from heat radiation in the event of a fire within the building by construction that will provide the same degree of protection that would be necessary if the member was located inside the building, with the protection extending on either side of the member a distance equal to the projection of the member from the face of the wall. (See also Article 3.2.3.9.)
Open OBC Div. B 3.2.2.3. in the code viewer
OBC Div. B 3.2.3.9. Protection of Structural Members
(1)Structural members, including beams, columns and arches, placed wholly or partly outside the exterior face of a building and are less than 3 m from the property line or the centre line of a public thoroughfare shall be protected from exterior fire exposure by fire protection having a fire-resistance rating not less than that required for their protection from interior fire exposure, as stated in Articles 3.2.2.20. to 3.2.2.93., but not less than 1 h.
(2)Structural members of heavy timber construction, including beams, columns and arches, that are placed wholly or partly outside an exterior face of a building and are 3 m or more from the property line or the centre line of a public thoroughfare need not be covered with noncombustible cladding.
Open OBC Div. B 3.2.3.9. in the code viewer
OBC Div. B 3.3.1.18. Guards
(1)Except as provided in Sentences (5) and (6) and Articles 3.3.2.9. and 3.3.4.7., a guard not less than 1,070 mm high shall be provided
(a)around each roof to which access is provided for other than maintenance,
(b)at openings into smoke shafts referred to in Subsection 3.2.6. that are less than 1,070 mm above the floor, and
(c)at each raised floor, mezzanine, balcony, gallery, interior or exterior vehicular ramp, and at other locations where (See Note A-9.8.8.1.)
(i)the difference in level is more than 600 mm between the walking surface and the adjacent surface, or
(ii)the adjacent surface within 1.2 m of the walking surface has a slope of more than 1 in 2, and
(d)except as provided in Sentence (6), around each skylight located in a portion of a roof that is intended to be occupied.
(2)Except as provided in Sentences (3) and 3.3.2.9.(4), openings through any guard that is required by Sentence (1) shall be of a size that will prevent the passage of a sphere having a diameter more than 100 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(2.1)Except as permitted by Sentence 3.3.5.10.(1), openings through any guard that is required by Sentence (1) and that is installed in a building of industrial occupancy shall be of a size which will prevent the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(3)Openings through any guard that is not required by Sentence (1) and that serves a building of other than industrial occupancy, shall be of a size that
(a)will prevent the passage of a sphere having a diameter more than 100 mm, or
(b)will permit the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings that exceed these limits do not represent a hazard. (See Note A-9.8.8.5.(4))
(4)Unless it can be shown that the location and size of openings do not present a hazard, a guard shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the level protected by the guard will facilitate climbing.
(5)Sentence (1) does not apply
(a)to the front edges of stages,
(b)to loading docks,
(c)to floor pits in repair garages, or
(d)where access is provided for maintenance purposes only.
(6)Clause (1)(d) does not apply to a skylight that
(a)is designed to support the loads specified in Part 4, or
(b)is provided with a skylight screen that
(i)has openings not more than 100 mm wide, and
(ii)can resist a concentrated load of 1.3 kN applied perpendicular at any point on the screen, without the deflection from this loading resulting in the breakage of the skylight glazing.
Open OBC Div. B 3.3.1.18. in the code viewer
OBC Div. B 3.4.6.6. Guards
(1)Every exit shall have a wall or a well-secured guard on each side, where
(a)the difference in elevation is more than 600 mm between the walking surface and the adjacent surface, or
(b)the adjacent surface within 1.2 m of the walking surface has a slope of more than 1 in 2. (See Note A-9.8.8.1.)
(2)Except as required by Sentence (4), the height of guards for exit stairs and exit ramps, as well as their landings, shall be not less than 1,070 mm.
(3)The height of guards shall be measured vertically to the top of the guard from
(a)a line drawn through the outside edges of the stair nosings, or
(b)the surface of the ramp or landing.
(4)The height of guards for exterior stairs and landings more than 10 m above adjacent ground level shall be not less than 1,500 mm measured vertically to the top of the guard from the surface of the landing or a line drawn through the outside edges of the stair nosings.
(5)Except as provided in Sentence (5.1), openings through any guard that is required by Sentence (1) shall be of a size that will prevent the passage of a sphere having a diameter more than 100 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(5.1)Openings through any guard that is required by Sentence (1) and that is installed in a building of industrial occupancy shall be of a size that will prevent the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(6)In a stairway, a window for which the distance measured vertically between the bottom of the window and a line drawn through the outside edges of the stair nosings is less than 900 mm, or a window that extends to less than 1,070 mm above the landing, shall
(a)be protected by a guard that is
(i)located approximately 900 mm above a line drawn through the outside edges of the stair nosings, or
(ii)not less than 1,070 mm high measured to the top of the guard from the surface of the landing, or
(b)be fixed in position and designed to resist the lateral design loads specified for guards and walls in Articles 4.1.5.14. and 4.1.5.16.
(7)Unless it can be shown that the location and size of openings do not present a hazard, a guard shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the level being protected by the guard will facilitate climbing.
Open OBC Div. B 3.4.6.6. in the code viewer
OBC Div. B 3.4.6.5. Handrails
(1)One handrail shall be provided on stairs that are less than 1,100 mm in width.
(2)One handrail shall be provided on each side of
(a)stairs that are 1,100 mm or more in width,
(b)curved flights of any width, and
(c)ramps.
(3)In addition to Sentence (2), intermediate handrails shall be provided so that
(a)a handrail is reachable within 825 mm of all portions of the required exit width, and
(b)at least one portion of the stair or ramp between two handrails is the required exit width for stairs or ramps as described in Sentences 3.4.3.2.(8) and 3.4.3.4.(4).
(4)Where a stair or ramp is wider than its required exit width, handrails shall be located along the most direct path of travel. (See Note A-3.4.6.5.(4))
(5)Handrails shall be continuously graspable along their entire length, be free of any sharp or abrasive elements, and have
(a)a circular cross-section with an outside diameter not less than 30 mm and not more than 50 mm, or
(b)a non-circular cross-section with a perimeter not less than 100 mm and not more than 160 mm and whose largest cross-sectional dimension is not more than 57 mm.
(6)The height of handrails on stairs, on aisles with steps and on ramps shall be measured vertically from the top of the handrail to
(a)a straight line drawn tangent to the tread nosings of the stair or aisle step served by the handrail, or
(b)the surface of the ramp, floor or landing served by the handrail.
(7)Except as provided in Sentence (8) and Clause 3.8.3.4.(1)(e), the height of handrails on stairs, on aisles with steps and on ramps shall be
(a)not less than 865 mm, and
(b)not more than 1070 mm.
(8)Handrails installed in addition to required handrails need not comply with Sentence (7).
(9)Required handrails shall be continuous throughout the length of
(a)a ramp, and
(b)a flight, from the bottom riser to the top riser. (See Note A-9.8.7.2.)
(10)Except as required by Sentence (16) and except where interrupted by doorways or newels at changes in direction, at least one handrail shall be continuous throughout the length of a stair or ramp, including at landings. (See Note A-3.4.6.5.(10))
(11)Handrails shall be terminated in a manner that will not obstruct pedestrian travel or create a hazard. (See Note A-3.4.6.5.(11))
(12)At least one handrail shall,
(a)in the case of a stair,
(i)extend horizontally at the required height, not less than 300 mm beyond the top riser, and
(ii)continue to slope for a depth of one tread beyond the bottom riser followed by a 300 mm horizontal extension, and
(b)in the case of a ramp, extend horizontally at the required height, not less than 300 mm beyond the top and bottom edges of the incline.
(13)The clearance between a handrail and any surface behind it shall be not less than
(a)60 mm, if the surface behind the handrail is rough or abrasive, or
(b)50 mm, in all other cases.
(14)Handrails and their supports shall be designed and constructed to withstand the loading values specified in Sentence 4.1.5.14.(7).
(15)A ramp shall have handrails on both sides.
(16)In a long-term care home, a Group B, Division 3 occupancy and a retirement home, a continuous handrail shall be provided on both sides of a stair throughout the length of the stair, including landings, except where a handrail is interrupted by doorways or newels at changes in direction.
Open OBC Div. B 3.4.6.5. in the code viewer
OBC Div. B 3.4.7.2. Fire Escape Construction
(1)Fire escapes shall be of metal or concrete, of the stair type extending to ground level, constructed throughout in a strong substantial manner and securely fixed to the building, except that wooden fire escapes are permitted to be used on buildings of combustible construction if all posts and brackets are not less than 89 mm in their least dimension and all other woodwork is not less than 38 mm in its least dimension.
Open OBC Div. B 3.4.7.2. in the code viewer
OBC Div. B 3.5.4.1. Elevator Car Dimensions
(1)Except as provided in Sentence (2), if an elevator is installed to conform to the requirements of Article 3.3.1.7., or if one or more elevators are provided in a building more than three storeys in building height, each storey having elevator service shall be served by at least one elevator that has inside dimensions that will accommodate and provide adequate access for a patient stretcher 2,010 mm long and 610 mm wide in the prone position. (See Note A-3.5.4.1.(1))
(2)The inside dimensions stipulated in Sentence (1) do not apply to limited-use/limited-application elevators designed and installed in accordance with ASME A17.1 / CSA B44, "Safety Code for Elevators and Escalators."
(3)An elevator satisfying the requirements of Sentence (1) shall be clearly identified on the main entrance level of the building.
Open OBC Div. B 3.5.4.1. in the code viewer
OBC Div. B 3.6.1.6. Fixed Access Ladders
(1)If a fixed ladder is installed to provide access to a roof of a building, the design and installation of the attachment and anchorage system for the ladder shall be as described in MMAH Supplementary Standard SB-8, "Design, Construction and Installation of Anchorage System for Fixed Access Ladders."
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OBC Div. B 3.6.2.7. Electrical Equipment Vaults
(1)Where an electrical equipment vault is required by the Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code) made under the Electricity Act, 1998, the electrical equipment vault shall be totally enclosed by a fire separation of solid masonry or concrete construction having a fire-resistance rating of not less than 3 h if the vault is not provided with an automatic fire extinguishing system and not less than 2 h if the vault is so protected.
(2)Where a building is required to be sprinklered throughout, the electrical equipment vault described in Sentence (1) need not be sprinklered provided
(a)the vault is designed for no purpose other than to contain the electrical equipment, and
(b)a smoke detector is provided in the vault that will actuate the building fire alarm system in the event of a fire in the vault.
(3)A vault, that is part of a building and houses electrical equipment indoors, shall have
(a)roofs or ceilings consisting of reinforced concrete of adequate strength for the conditions and not less than 150 mm thick, and
(b)floors consisting of reinforced concrete of adequate strength for the conditions and not less than 150 mm thick, except that floors that are at excavation level are permitted to be of reinforced concrete not less than 100 mm thick.
(4)Walls, roofs or ceilings, and floors shall be adequately anchored together in a manner designed to resist dislodgement by explosion.
(5)Only pipes or ducts necessary for fire protection or the proper operation of the electrical installation shall penetrate the fire separations surrounding the electrical equipment vault.
(6)A ventilation duct or opening, that penetrates the fire separation to the outdoors, need not be protected by a closure at the penetration.
(7)Each door to an electrical equipment vault shall be provided with a substantial lock or padlock.
(8)Explosion-relief devices and vents or other protective measures shall be provided for every electrical equipment vault containing dielectric liquid-filled electrical equipment in conformance with Sentence 3.3.1.21.(3). (See Note A-3.6.2.7.(8))
(9)Every electrical equipment vault shall be provided with a ventilation system designed in conformance with Part 6 to prevent the ambient temperature in the vault from exceeding 40 ° C.
(10)Where the vault ventilation system in Sentence (9) is directly from an outdoor area by natural ventilation without the use of ducts, and where the electrical equipment is the principal source of heat, the combined net area of inlet and outlet openings shall be not less than 0.002 m² / kVa of electrical equipment capacity with a minimum of 0.093 m² , except that
(a)where equipment in the power class as described in CAN/CSA-C88-M, "Power Transformers and Reactors" is installed, ventilation requirements are permitted to be based on the actual full-load losses, or
(b)where the equipment is installed for emergency purposes only and is not normally energized, it need not be considered in determining the ventilation requirements.
(11)In the vault ventilation system in Sentence (10), the inlet for fresh air shall lead from an outdoor area and shall terminate at a point not more than 1,000 mm above the floor level of the vault.
(12)Where the vault ventilation system in Sentence (9) is a mechanical system, it shall be separate from the system for the remainder of the building and shall be designed so that
(a)the vault temperature is thermostatically controlled,
(b)the fan is located so that it may be serviced without danger to personnel,
(c)a high temperature alarm is provided in the vault,
(d)the system is automatically shut off in the event of a fire in the vault, and
(e)a filter is provided in the air inlet if there is a possibility of dirt being drawn in.
(13)All ventilation openings shall be protected in conformance with Sentences 6.3.2.9.(4) and (5) and the protection shall be installed in such a manner that it cannot be removed from the outside by the use of common tools and it is tamperproof.
(14)Except as permitted in Sentence (15), the floor of an electrical equipment vault referred to in Sentences (1) and (2) shall be liquid tight and surrounded by liquid tight walls and sills of sufficient height to confine within the vault all of the liquid from the largest item of electrical equipment, but to a height of not less than 100 mm.
(15)The floor of the electrical equipment vault described in Sentences (1) and (2) may be provided with a floor drain connected to a covered sump capable of holding all of the liquid from the largest item of electrical equipment, and the connection shall have a noncombustible trap to prevent the spread of fire from the vault to the sump.
(16)Where the electrical equipment vault is located in a hazardous location classified as Class II, Division 1 in accordance with the Electrical Safety Code adopted under Ontario Regulation 164/99 (Electrical Safety Code) made under the Electricity Act, 1998, it shall have
(a)no vent opening except to the exterior of the building, and
(b)suitable pressure-relief openings communicating only with the air outside the building.
(17)Where doors are provided between the vault described in Sentence (16) and the rest of the building, they shall have suitable seals such as weatherstripping to minimize the entrance of dust into the vault.
(18)Every electrical equipment vault shall be provided with
(a)adequate lighting, controlled by one or more switches located near the entrance,
(b)luminaires located so that they may be relamped without danger to personnel, and
(c)a grounded receptacle located in a convenient location inside the vault, near the entrance.
Open OBC Div. B 3.6.2.7. in the code viewer
OBC Div. B 3.15.3.1. Structural Design
(1)Except as provided in this Section, all sign structures shall be designed in accordance with Part 4.
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OBC Div. B 3.16.1.3. Construction
(1)All structural components of a shelf and rack storage system, including posts, beams, decks, walkways, connections and their supports such as concrete slabs and foundations, shall be designed in accordance with Part 4.
(2)Except as required by Sentence 3.16.3.2.(2), platform and walkway levels shall be of
(a)solid construction consisting of steel plate or steel roof decking with a top substrate that forms a serviceable floor area, or
(b)open construction consisting of steel grating or open steel floor planking.
(3)Guards and toe-boards shall be provided in accordance with Articles 3.3.1.18. and 3.3.5.11.
(4)Every platform or walkway level shall be provided with fire extinguishers installed in conformance with the Fire Code made under the Fire Protection and Prevention Act, 1997.
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OBC Div. B 3.10.2.3. Structural Fire Protection
(1)Except as provided in Sentence 3.10.4.2.(1), the requirements in Subsections 3.2.1. and 3.2.2. shall apply.
(2)The first storey shall be subdivided into areas not more than 500 m² by a masonry or reinforced concrete fire separation having a fire-resistance rating not less than 1 h, or it shall be sprinklered.
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OBC Div. B 3.18.1.1. Application
(1)This Section applies where proposed construction
(a)in respect of an existing building will result in any of the following changes of use of all or part of the building:
(i)a change of the major occupancy of all or part of a building that is designated with a "Y" in Table 1.3.1.4. of Division C,
(ii)a suite of a Group C major occupancy is converted into more than one suite of a Group C major occupancy,
(iii)a suite or part of a suite of a Group A, Division 2 or a Group A, Division 4 major occupancy is converted to a gaming premises,
(iv)a farm building or part of a farm building is changed to a major occupancy,
(v)a building or part of a building is changed to a post-disaster building,
(vi)a building or part of a building is changed to a retirement home, or
(vii)the use of a building or part of a building is changed and the previous major occupancy of the building or part of the building cannot be determined, or
(b)in respect of an existing building of combustible construction will extend the building by adding a storey or storeys such that the extended building will be more than four storeys in building height.
(2)For the purposes of this Section and Sentences 11.4.2.1.(1) and 11.4.2.5.(4), the changes of use set out in Subclauses (1)(a)(ii) to (iv) and (vi) shall also be deemed to constitute a change in major occupancy.
(3)The requirements of this Section are in addition to the requirements of other Parts of this Division as they apply to the proposed construction.
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