Guard and firewall loads, environmental separation and HVAC items (Large Buildings)

Last updated October 22, 2026

Values this chapter turns on

outward guard load at grandstand and arena egress: 3.0 kN/m; outward guard load at grandstand and arena egress
minimum outward load on a wall acting as a guard: 0.5 kPa; minimum outward load on a wall acting as a guard
indoor heating design for Group C and B-2 or B-3: 22°C; indoor heating design for Group C and B-2 or B-3
test pressure for air barrier leakage classes: 75 Pa; test pressure for air barrier leakage classes

This section pulls a handful of structural, envelope and mechanical provisions into the Large Buildings exam. Part 4 contributes three load Articles, Part 5 comes in whole, and Part 6 contributes a selected list. Most of Part 5 is written as performance language ("minimize", "control", "unless it can be shown"), so expect questions on its few hard numbers and on the conditions that switch a requirement on or off.

Loads on guards, walls acting as guards and firewalls

OBC Div. B 4.1.5.14. sets the specified live loads for guards and handrails in Part 3 buildings. Our summary:

Location or element	Load
Guard, outward, grandstands, stadia, bleachers, arenas (egress) and open viewing stands	3.0 kN/m
Guard, outward, equipment access ways where crowds are unlikely	1.0 kN at any point
Guard, outward, all other locations	0.75 kN/m or 1.0 kN, whichever governs
Guard, inward	Half the outward value
Individual elements (pickets, panels)	0.5 kN over 100 mm by 100 mm
Vertical load on top of guard	1.5 kN/m
Handrails	0.9 kN any point; 0.7 kN/m outside dwelling units

None of the guard element loads need to act at the same time as the main guard loads.

A wall acts as a guard where the floor on one side is more than 600 mm higher than on the other, including walls around shafts. It must resist 0.5 kPa outward or the other Part 4 lateral loads, whichever is worse (4.1.5.16.). A firewall must resist its normal lateral loads or a factored 0.5 kPa under fire conditions; where the structure on one side has a lower fire-resistance rating than the firewall, the design assumes support from one side only, or a separate support system is provided (4.1.5.17.).

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Part 5: environmental separation

Part 5 applies to assemblies exposed to the exterior or the ground and to assemblies separating environmentally dissimilar interior spaces (5.1.2.1.). Climatic loads come from SB-1 (5.2.1.1.). Assemblies must resist structural loads determined under Part 4, and the wind load used is 100% of the specified wind load unless a test or analysis shows less (5.2.2.2.).

The Part 5 pattern to remember: heat transfer, air leakage, vapour diffusion, precipitation and ground water each have a "provide protection" rule followed by an exemption where it can be shown that leaving the protection out will not hurt health or safety, the intended use or the building services. Examples are 5.3.1.1., 5.4.1.1. and 5.5.1.1..

Air barriers. The air barrier system provides the principal resistance to air leakage and must be continuous across joints, junctions and penetrations. Its assemblies meet a Performance Class in Table 5.4.1.1., which runs from Class 1 (tightest) to Class 5 at a test pressure of 75 Pa. Class 3, for example, allows 0.15 L/(s x m²). Below-grade air barriers must also limit radon and other soil gases (5.4.1.2.).

Ground water. Walls and floors against the ground are waterproofed unless the building is designed to accept the water or it does no harm (5.7.3.2.). Dampproofing is allowed only for vertical assemblies when three conditions are all true: no hydrostatic pressure, a cast-in-place concrete substrate and a drainage layer against the soil (5.7.3.4.).

Sound. A dwelling unit is separated from other spaces where noise may be generated by ASTC 47, or STC 50 with flanking construction to 9.11.1.4. Next to an elevator shaft or refuse chute the requirement is STC 55 (5.8.1.1.). Ratings come from tests, calculation methods in 5.8.1.4. and 5.8.1.5., or the SB-3 tables.

Fenestration. Windows, doors and skylights follow the North American fenestration standard and its Canadian supplement (5.9.2.2.), and metal-framed assemblies need a thermal break except storm units and fire-rated doors and windows (5.9.2.4.). "Other fenestration assemblies" means curtain walls, window walls, storefronts and glazed architectural structures (5.9.3.1.); their air leakage limit is 0.2 L/(s x m²) for fixed portions and 1.5 for operable portions, with a list of exempt systems such as revolving doors and commercial entrance systems (5.9.3.4.).

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Part 6: design and installation

HVAC systems follow good engineering practice, with the Code naming the ASHRAE, HRAI, SMACNA and similar publications as examples (6.2.1.1.). Do not expect questions that need those documents; expect questions on the Code's own values.

Item	Value	Source
Heating capacity, Group B2/B3 and Group C buildings used in winter	22°C indoors	6.2.1.1A.
Heating capacity, other buildings	18°C indoors	6.2.1.1A.
Combustible pneumatic tubing in noncombustible buildings	10 mm outside diameter max	6.2.1.8.
Solid fuel storage bin temperature	Below 50°C	6.2.3.1.
Grilles on openings less than 2 m above floor	Stop a 15 mm sphere	6.3.2.9.
Outdoor air intake above roofs and grade	At least 0.3 m	6.3.2.9.
Radiator surface temperature	70°C unless contact is prevented	6.7.1.3.

Asbestos is banned from HVAC systems (6.2.1.7.), and equipment that needs maintenance must be accessible (6.2.1.6.).

Ducts. Duct materials and coverings point back to Part 3 (3.6.5.1. and 3.6.5.4.), and duct linings must not interfere with dampers or fire stop flaps (6.3.2.3., 6.3.2.5.).

Air intakes. Table 6.3.2.9. gives minimum distances from contaminant sources. The large values (7.6 m) are truck docks and bus parking, busy roads and evaporative heat rejection discharge. Garage entries and garbage areas are 4.5 m, sanitary vents 3.5 m, kitchen exhausts and solid fuel vents 3.0 m, and quiet driveways 1.5 m.

Venting. Products of combustion not covered by an appliance standard are discharged at least 2.15 m above sidewalks and driveways and 3 m from air intakes, doors, operable windows and occupied outdoor spaces (6.3.3.1.).

Piping. Bare steam or hot water pipes need no clearance to combustibles up to 95°C, 15 mm above 95°C up to 120°C, and 25 mm above 120°C (Table 6.7.1.2.).

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Hazardous gases and carbon monoxide alarms

Systems serving spaces with hazardous gases, dusts or liquids follow the Fire Code, or good practice where it is silent, and trenches for Class I flammable liquid piping are ventilated or designed to prevent vapour build-up (6.9.1.2.).

The carbon monoxide rules in 6.9.3.1. work in two layers. Suite rules (6.9.3.2.) apply only where a building has residential occupancy or care occupancy suites or sleeping rooms with a fuel-burning appliance or storage garage. Service room rules (6.9.3.3.) and installation rules (6.9.3.4.) apply to every building.

In a suite: an alarm where a fuel appliance or flue is in the suite, where forced air heat from a fuel appliance enters it, or where an appliance, flue or storage garage shares a wall, floor or ceiling with it (6.9.3.2.). Place them next to each sleeping room and on each storey without one.
Public corridors heated directly by a forced-air fuel-burning appliance: alarms at most 25 m apart.
Service rooms with fuel-burning building service or laundry drying equipment: an alarm in every building (6.9.3.3.).
Installation: hard-wired with battery backup (8 h standby then 12 h alarm), interconnected within the suite or corridor (6.9.3.4.).

Fireplaces go to Section 9.22. (6.9.4.2.).

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Common traps

Using the outward guard load where the question asks for the inward load.
Allowing dampproofing on block walls.
Thinking CO alarms are only for residential buildings: the service room rule covers all buildings.

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
Loads on guards, walls acting as guards and firewalls	None of the guard element loads need to act at the same time as the main guard loads.
Part 5: environmental separation	Part 5 applies to assemblies exposed to the exterior or the ground and to assemblies separating environmentally dissimilar interior spaces.
Part 6: design and installation	HVAC systems follow good engineering practice, with the Code naming the ASHRAE, HRAI, SMACNA and similar publications as examples.
Hazardous gases and carbon monoxide alarms	Systems serving spaces with hazardous gases, dusts or liquids follow the Fire Code, or good practice where it is silent, and trenches for Class I flammable liquid piping are…

Loads on guards, walls acting as guards and firewalls
None of the guard element loads need to act at the same time as the main guard loads.
Part 5: environmental separation
Part 5 applies to assemblies exposed to the exterior or the ground and to assemblies separating environmentally dissimilar interior spaces.
Part 6: design and installation
HVAC systems follow good engineering practice, with the Code naming the ASHRAE, HRAI, SMACNA and similar publications as examples.
Hazardous gases and carbon monoxide alarms
Systems serving spaces with hazardous gases, dusts or liquids follow the Fire Code, or good practice where it is silent, and trenches for Class I flammable liquid piping are…

Usual exam traps

Using the outward guard load where the question asks for the inward load.
Allowing dampproofing on block walls.
Thinking CO alarms are only for residential buildings: the service room rule covers all buildings.

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Questions on Structural, environmental separation and HVAC items, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

Practice this chapter Free Large Buildings quiz

Code cited in this chapter

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

OBC Div. B 4.1.5.14. Loads on Guards and Handrails)
(1)The minimum horizontal specified live load applied outward at the minimum required height of every required guard shall be
(a)3.0 kN/m for open viewing stands without fixed seats and for means of egress in grandstands, stadia, bleachers and arenas,
(b)1.0 kN applied at any point, so as to produce the most critical effect, for access ways to equipment platforms, contiguous stairs and similar areas where the gathering of many people is improbable, and
(c)0.75 kN/m or 1.0 kN applied at any point so as to produce the most critical effect, whichever governs for locations other than those described in Clauses (a) and (b).
(2)The minimum horizontal specified live load applied inward at the minimum required height of every required guard shall be half that specified in Sentence (1).
(3)Individual elements within the guard, including solid panels and pickets, shall be designed for a horizontal specified live load of 0.5 kN applied outward over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect.
(4)The size of the opening between any two adjacent vertical elements within a guard shall not exceed the limits required by Part 3 when each of these elements is subjected to a horizontal specified live load of 0.1 kN applied in opposite directions in the in-plane direction of the guard so as to produce the most critical effect.
(5)The specified live loads required in Sentence (3) need not be considered to act simultaneously with the loads provided for in Sentences (1), (2), (6) and (7).
(6)The minimum specified live load applied vertically at the top of every required guard shall be 1.5 kN/m and need not be considered to act simultaneously with the horizontal specified live load provided for in Sentences (1), (3) and (7).
(7)Handrails and their supports shall be designed and constructed to withstand the following minimum specified live loads, which need not be considered to act simultaneously:
(a)0.9 kN applied at any point and in any direction for all handrails, and
(b)0.7 kN/m applied in any direction for handrails not located within dwelling units.
Open OBC Div. B 4.1.5.14. in the code viewer
OBC Div. B 4.1.5.16. Loads on Walls Acting As Guards
(1)Where the floor elevation on one side of a wall, including a wall around a shaft, is more than 600 mm higher than the elevation of the floor or ground on the other side, the wall shall be designed to resist the appropriate outward lateral design loads prescribed elsewhere in Subsection 4.1.5. or 0.5 kPa acting outward, whichever produces the more critical effect.
Open OBC Div. B 4.1.5.16. in the code viewer
OBC Div. B 4.1.5.17. Firewalls
(1)Firewalls shall be designed to resist the maximum effect due to,
(a)the appropriate lateral design loads prescribed elsewhere in this Section, or
(b)a factored lateral load of 0.5 kPa under fire conditions, as described in Sentence (2).
(2)Under fire conditions, where the fire-resistance rating of the structure is less than that of the firewall,
(a)lateral support shall be assumed to be provided by the structure on one side only, or
(b)another structural support system capable of resisting the loads imposed by a fire on either side of the firewall shall be provided.
Open OBC Div. B 4.1.5.17. in the code viewer
OBC Div. B 5.1.2.1. Exposure to Exterior Space or the Ground and Separation of Dissimilar Environments
(1)This Part applies to
(a)building materials, components and assemblies exposed to exterior space or the ground, including those separating interior space from exterior space or separating interior space from the ground,
(b)building materials, components and assemblies separating environmentally dissimilar interior spaces, and (See Note A-5.8.)
(c)site materials, components, assemblies and grading that may affect environmental loads on building materials, components and assemblies exposed to exterior space or the ground. (See Note A-5.1.2.1.(1))
Open OBC Div. B 5.1.2.1. in the code viewer
OBC Div. B 5.2.1.1. Exterior Environmental Loads
(1)Above ground climatic loads shall be determined according to MMAH Supplementary Standard SB-1, "Climatic and Seismic Data."
(2)Except as provided in Sentence (3), below ground exterior environmental loads not described in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," shall be determined from existing geological and hydrological data or from site tests.
(3)Where local design and construction practice has shown soil temperature analysis to be unnecessary, soil temperatures need not be determined. (See Note A-5.2.1.1.(3))
Open OBC Div. B 5.2.1.1. in the code viewer
OBC Div. B 5.2.2.2. Determination of Wind Load
(1)This Article applies to the determination of wind load to be used in the design of materials, components and assemblies, including their connections, that separate dissimilar environments or are exposed to the exterior, where these are,
(a)subject to wind load, and
(b)required to be designed to resist wind load.
(2)Except as provided in Sentence (3), the wind load referred to in Sentence (1) shall be 100% of the specified wind load determined in accordance with Article 4.1.7.1.
(3)Where it can be shown by test or analysis that a material, component, assembly or connection referred to in Sentence (1) will be subject to less than 100% of the specified wind load, the wind load referred to in Sentence (1) shall be not less than the load determined by test or analysis.
(4)Except as provided in Sentence (5), the wind uplift resistance of membrane roofing assemblies shall be determined in accordance with the requirements of CAN/CSA A123.21, "Standard test method for the dynamic wind uplift resistance of membrane-roofing systems." (See Note A-5.2.2.2.(4))
(5)Membrane roofing assemblies with proven past performance for the anticipated wind loads need not comply with Sentence (4). (See Note A-5.1.4.1.(5))
Open OBC Div. B 5.2.2.2. in the code viewer
OBC Div. B 5.3.1.1. Required Resistance to Heat Transfer
(1)Except as provided in Sentence (2), where a building component or assembly will be subjected to an intended temperature differential, the component or assembly shall include materials to resist heat transfer or a means to dissipate transferred heat in accordance with the remainder of this Subsection.
(2)The installation of materials to resist heat transfer in accordance with this Subsection is not required where it can be shown that uncontrolled heat transfer will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.3.1.1. in the code viewer
OBC Div. B 5.4.1.1. Required Resistance to Air Leakage (Note A-5.4.1.1.)
(1)Where a building component or assembly separates interior conditioned space from exterior space, interior space from the ground, or environmentally dissimilar interior spaces, the properties and position of the materials and components in those components or assemblies shall be such that they control air leakage or permit venting to the exterior so as to
(a)provide acceptable conditions for the building occupants,
(b)maintain appropriate conditions for the intended use of the building,
(c)minimize the accumulation of condensation in and the penetration of precipitation into the building component or assembly,
(d)control heat transfer to roofs where ice damming can occur,
(e)minimize the ingress of airborne radon and other soil gases from the ground with an aim to controlling the indoor concentrations of these gases to an acceptable level, and
(f)not compromise the operation of building services.
(2)Except as provided in Sentence (7), an air barrier system shall be designed and constructed to provide the principal resistance to air leakage to meet the requirements of Sentence (1).
(3)The air barrier system shall incorporate air barrier assemblies that meet the appropriate Performance Class as defined in Table 5.4.1.1. (See Note A-5.4.1.1.(3))
(4)The air barrier system shall be designed and constructed to be continuous
(a)across construction, control and expansion joints,
(b)across junctions between different air barrier assemblies, and
(c)around penetrations through air barrier assemblies. (See Note A-5.4.1.1.(4))
(5)The structural design of air barrier assemblies, including junctions between air barrier assemblies, subject to air pressure loads shall comply with Article 5.1.4.1. and Subsection 5.2.2.
(6)The maximum air leakage rates specified in Table 5.4.1.1. are permitted to be increased where it can be shown that the higher rate will not adversely affect any of
(a)the health or safety of the building users,
(b)the intended use of the building, or
(c)the operation of building services.
(7)An air barrier system is not required where it can be shown that uncontrolled air leakage will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services. (See Note A-5.4.1.1.(7))
Open OBC Div. B 5.4.1.1. in the code viewer

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OBC Div. B 5.5.1.1. Required Resistance to Vapour Diffusion
(1)Where a building component or assembly is subjected to differentials in temperature and water vapour pressure, the properties and position of the materials and components in those components or assemblies shall be such that they control vapour diffusion or permit venting to the exterior so as to minimize accumulation of condensation in the building component or assembly.
(2)Except as provided in Sentence (3), a vapour barrier shall be installed to provide the principal resistance to water vapour diffusion.
(3)A vapour barrier is not required where it can be shown that uncontrolled vapour diffusion will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.5.1.1. in the code viewer
OBC Div. B Table 5.4.1.1. Maximum Air Leakage Rates for Air Barrier Assemblies — Forming Part of Sentences 5.4.1.1.(3) and (6) and 5.4.1.2.(1) and (2)
Table 5.4.1.1. Maximum Air Leakage Rates for Air Barrier Assemblies — Forming Part of Sentences 5.4.1.1.(3) and (6) and 5.4.1.2.(1) and (2) Performance Class | Maximum Air Leakage Rate, L / (s × m²), at a Pressure Differential of 75 Pa 1 | 0.05 2 | 0.10 3 | 0.15 4 | 0.20 5 | 0.50
Open OBC Div. B Table 5.4.1.1. in the code viewer
OBC Div. B 5.4.1.2. Air Barrier Assemblies
(1)Except as provided in Sentences (2) and (3), air barrier assemblies not in contact with the ground shall
(a)conform with CAN/ULC-S742, "Standard for Air Barrier Assemblies – Specification," and
(b)meet the selected Performance Class of Table 5.4.1.1. (See Note A-5.4.1.2.(1))
(2)Air barrier assemblies not evaluated in accordance with CAN/ULC-S742, "Standard for Air Barrier Assemblies – Specification," shall be designed and constructed
(a)to meet or exceed the selected Performance Class of Table 5.4.1.1., and
(b)with at least one air barrier material intended to provide the primary resistance to air leakage that meets the requirements of CAN/ULC-S741, "Standard for Air Barrier Materials – Specification." (See Note A-5.4.1.2.(2))
(3)Air barrier assemblies covered in Subsections 5.9.2., 5.9.3. and 5.9.4. shall meet the air barrier performance criteria defined in those Subsections.
(4)Below-grade air barrier assemblies in contact with the ground shall minimize the ingress of airborne radon and other soil gases. (See Note A-5.4.1.2.(4))
Open OBC Div. B 5.4.1.2. in the code viewer
OBC Div. B 5.7.3.2. Required Protection
(1)Except as provided in Sentence (2) and Article 5.7.3.4., building assemblies described in Article 5.7.3.1. shall be protected by waterproofing in accordance with Article 5.7.3.3. so as to minimize the ingress of water into the building or the accumulation of water against the building.
(2)Waterproofing is not required where it can be shown that
(a)a building is designed to accommodate the ingress or accumulation of ground water, or
(b)the ingress or accumulation of ground water will not negatively affect
(i)the health or safety of building users,
(ii)the intended use of the building, or
(iii)the operation of building services.
Open OBC Div. B 5.7.3.2. in the code viewer
OBC Div. B 5.7.3.4. Where Dampproofing is Permitted
(1)Vertical building assemblies that separate interior space from the ground are permitted to be dampproofed where,
(a)such assemblies are not subjected to hydrostatic pressure,
(b)the substrate is cast-in-place concrete, and
(c)a drainage layer is installed between the building assembly and the soil.
(See Note A-5.7.3.4.(1))
(2)Joints, junctions and penetrations shall be designed and constructed to maintain the continuity of the dampproofing.
Open OBC Div. B 5.7.3.4. in the code viewer
OBC Div. B 5.8.1.1. Required Protection
(1)Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by
(a)a separating assembly and adjoining constructions, which, together, provide an apparent sound transmission class (ASTC) rating not less than 47, or
(b)a separating assembly that provides a sound transmission class (STC) rating of not less than 50 and adjoining constructions that conform to Article 9.11.1.4.
(2)Construction separating a dwelling unit from an elevator shaft or a refuse chute shall have an STC rating not less than 55.
Open OBC Div. B 5.8.1.1. in the code viewer
OBC Div. B 5.9.2.2. Applicable Standards
(1)Windows, doors and skylights shall conform to the requirements in
(a)AAMA/WDMA/CSA 101/I.S.2/A440, "North American Fenestration Standard/Specification for windows, doors, and skylights" (Harmonized Standard), and
(b)CSA A440S1, "Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440-17, North American Fenestration Standard/Specification for windows, doors, and skylights."
(2)Performance grades for windows, doors and skylights shall be selected according to the Canadian Supplement referenced in Clause (1)(b) so as to be appropriate for the conditions and geographic location in which the window, door or skylight will be installed.
(3)Windows, doors and skylights shall conform to the performance grades selected in Sentence (2) when tested in accordance with the Harmonized Standard referenced in Clause (1)(a).
Open OBC Div. B 5.9.2.2. in the code viewer
OBC Div. B 5.9.2.4. Heat Transfer
(1)Windows, doors and skylights shall meet the heat transfer performance requirements stated in Section 5.3. (See Note A-5.3.1.2.)
(2)Except as provided in Sentence (3), all metal-framed glazed assemblies separating interior conditioned space from interior unconditioned space or exterior space shall incorporate a thermal break to minimize condensation.
(3)Metal-framed glazed assemblies need not comply with Sentence (2) where these assemblies are
(a)storm windows or doors, or
(b)windows or doors that are required to have a fire-protection ratings. (See Note A-5.9.2.4.(3))
Open OBC Div. B 5.9.2.4. in the code viewer
OBC Div. B 5.9.3.1. Definition
(1)In this Subsection, "other fenestration assemblies" means curtain walls, window walls, storefronts and glazed architectural structures. (See Note A-5.9.3.1.(1))
Open OBC Div. B 5.9.3.1. in the code viewer
OBC Div. B 5.9.3.4. Air Leakage
(1)Other fenestration assemblies and their components shall be designed and constructed in accordance with Section 5.4.
(2)Except as provided in Sentence (3), other fenestration assemblies and their components shall have "Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen," that is not greater than
(a)0.2L/(s × m^2) for fixed portions, including any opaque portions, and
(b)1.5L/(s × m^2) for operable portions. (See Note A-5.9.3.4.(2))
(3)The following systems need not comply with Sentence (2):
(a)interior windows and interior doors that do not serve as environmental separators,
(b)vehicular access doors (garage doors),
(c)storm windows and storm doors,
(d)commercial entrance systems,
(e)revolving doors,
(f)smoke and relief air vents,
(g)site-built door systems, and
(h)commercial steel doors. (See Note A-5.9.3.4.(3))
Open OBC Div. B 5.9.3.4. in the code viewer
OBC Div. B 6.2.1.1. Good Engineering Practice
(1)Heating, ventilating and air-conditioning systems, including mechanical refrigeration equipment, shall be designed, constructed and installed in conformance with good engineering practice such as that described in, but not limited to,
(a)the ASHRAE Handbooks and Standards,
(b)the HRAI Digest,
(c)the Hydronics Institute Manuals,
(d)the NFPA Standards,
(e)the SMACNA Manuals,
(f)the ACGIH manual entitled "Industrial Ventilation: A Manual of Recommended Practice for Design,"
(g)CSA B214, "Installation code for hydronic heating systems,"
(h)CAN/CSA-Z317.2, "Special requirements for heating, ventilation, and air-conditioning (HVAC) systems in health care facilities,"
(i)EPA 625/R-92/016, "Radon Prevention in the Design and Construction of Schools and Other Large Buildings," and
(j)ASHRAE Guideline 12, "Minimizing the Risk of Legionellosis Associated with Building Water Systems."
Open OBC Div. B 6.2.1.1. in the code viewer
OBC Div. B 6.2.1.1A. Design Indoor Air Temperatures
(1)Buildings classified as Group B, Division 2 or 3 occupancies or Group C residential occupancies that are intended for use in the winter months on a continuing basis shall be insulated and be equipped with heating facilities that are capable of maintaining an indoor air temperature of 22°C at the outside winter design temperature referred to in Article 6.2.1.2.
(2)All other buildings intended for occupancy in the winter months on a continuing basis should be insulated and shall be equipped with heating facilities to maintain a minimum indoor air temperature of 18°C or commensurate with the use of the building at the outside winter design temperature described in Article 6.2.1.2.
Open OBC Div. B 6.2.1.1A. in the code viewer
OBC Div. B 6.2.1.8. Combustible Tubing
(1)Combustible tubing for pneumatic controls may be used in buildings required to be of noncombustible construction provided it has an outside diameter not exceeding 10 mm.
Open OBC Div. B 6.2.1.8. in the code viewer
OBC Div. B 6.2.3.1. Solid Fuel Storage Bins
(1)A storage bin for solid fuel shall not be located above a sewer opening or drain opening.
(2)Storage bins for solid fuel shall be designed and constructed so that the air temperature in the bin or the surface temperature of any part of the floor or walls is below 50°C.
Open OBC Div. B 6.2.3.1. in the code viewer
OBC Div. B 6.3.2.9. Supply, Return, Intake and Exhaust Air Openings
(1)Supply, return and exhaust air openings located less than 2 m above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diam sphere.
(2)Outdoor air intakes shall be located so that
(a)the quality of the air entering the building complies with Sentence 6.2.1.2.(1), and
(b)they are separated a minimum distance from sources of contaminants in accordance with Table 6.3.2.9.
(3)Outdoor air intakes shall be installed not less than 0.3 m above roofs, landscape grades or other surfaces, taking into account anticipated snow accumulation levels.
(4)Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to prevent the screen openings from icing over.
(5)Screens required in Sentence (4) shall be accessible for maintenance.
(6)Combustible grilles, diffusers and other devices covering supply, return, intake and exhaust openings shall comply with Article 3.6.5.7.
Open OBC Div. B 6.3.2.9. in the code viewer
OBC Div. B 6.7.1.3. Surface Temperature
(1)The exposed surface temperature of a steam or hot water radiator shall not exceed 70°C unless precautions are taken to prevent human contact. (See Note A-6.5.1.1.(3))
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OBC Div. B 6.2.1.7. Asbestos
(1)Asbestos shall not be used in heating, ventilating or air-conditioning systems or equipment.
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OBC Div. B 6.2.1.6. Installation — General
(1)Equipment requiring periodic maintenance and forming part of a heating, ventilating or air-conditioning system shall be installed with provision for access for inspection, maintenance, repair and cleaning. (See Note A-6.2.1.6.(1))
(2)Mechanical equipment shall be provided with guards so as to prevent injury.
(3)Heating, ventilating or air-conditioning systems shall be protected from freezing if they may be adversely affected by freezing temperatures.
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OBC Div. B 6.3.2.3. Materials in Air Duct Systems
(1)All ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of materials as described in Article 3.6.5.1.
(2)Ducts that are used in a location where they may be subjected to excessive moisture shall have no appreciable loss of strength when wet and shall be resistant to moisture-induced corrosion.
(3)All ductwork and fittings shall be constructed and installed as recommended in SMACNA Manuals and ASHRAE Standards.
(4)All duct materials shall be suitable for exposure to the temperature and humidity of the air being carried and shall be resistant to corrosion caused by contaminants in the air being conveyed in the duct.
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OBC Div. B 6.3.2.5. Duct Coverings, Linings, Adhesives and Insulation
(1)Coverings, linings and associated adhesives and insulation used in air ducts, plenums and other parts of air duct systems shall comply with Article 3.6.5.4.
(2)Duct linings shall be installed so that they will not interfere with the operation of volume or balancing dampers or of fire dampers, fire stop flaps and other closures.
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OBC Div. B Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2)
Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2) Source of Contaminants | Minimum Distance of Outdoor Air Intake, m Garage entry of a garage for 5 or more motor vehicles, automobile loading area and drive-in queue | 4.5 Truck loading area or dock, and bus parking | 7.6 Driveway, parking space, lane, road and similar locations that carry a low volume of traffic | 1.5 Thoroughfare, arterial road, freeway, highway and similar locations that carry a high volume of traffic | 7.6 Garbage storage/pick-up area and dumpsters | 4.5 Discharge from evaporative heat rejection systems | 7.6 Sanitary vent | 3.5 Kitchen exhaust outlet | 3.0 Vent for combustion products from solid fuel-burning appliances | 3.0
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OBC Div. B 6.3.3.1. Requirement for Venting
(1)Except as provided in Articles 6.3.3.2. and 6.3.3.3., the products of combustion from oil-, gas and solid-fuel-burning appliances shall be vented in conformance with the requirements in the applicable appliance installation standard listed in Article 6.2.1.5.
(2)Except as provided in Article 6.2.1.5., vented products of combustion, other than those referred to in Sentence (1), shall be discharged away from the building, so as not to re-enter it, to a distance not less than
(a)2.15 m above sidewalks and driveways,
(b)3 m from outdoor air intakes,
(c)3 m horizontally or vertically from doors and operable windows, and
(d)3 m horizontally or vertically from occupiable outdoor spaces, excluding maintenance spaces. (See Note A-6.3.3.1.(2))
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OBC Div. B Table 6.7.1.2. Clearance Between Steam or Hot Water Pipes and Combustible Material — Forming Part of Article 6.4.2.1., Sentence 6.4.3.1.(2) and Article 6.7.1.2.
Table 6.7.1.2. Clearance Between Steam or Hot Water Pipes and Combustible Material — Forming Part of Article 6.4.2.1., Sentence 6.4.3.1.(2) and Article 6.7.1.2. Steam or Water Temperature, °C | Minimum Clearance, mm Up to 95 | No clearance Above 95 to 120 | 15 mm Above 120 | 25 mm
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OBC Div. B 6.9.1.2. Hazardous Gases, Dusts or Liquids
(1)Except as provided in Subsection 6.3.4., systems serving spaces that contain hazardous gases, dusts or liquids shall be designed, constructed and installed in conformance with the provisions of the Fire Code made under the Fire Protection and Prevention Act, 1997, or in the absence of requirements pertinent to such systems in the Fire Code, to good engineering practice such as that described in the publications of the National Fire Protection Association and in the CCBFC NRCC-CONST-56437E, "National Fire Code of Canada. (See Note A-6.9.1.2.(1))
(2)When indoor piping for Class I flammable liquids is installed in a trench, the trench shall be
(a)provided with positive ventilation to the outdoors, or
(b)designed to prevent the accumulation of flammable vapours.
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OBC Div. B 6.9.3.1. Application
(1)Article 6.9.3.2. applies to every building that
(a)contains a residential occupancy, a care occupancy with individual suites, or a care occupancy containing sleeping rooms not within a suite, and contains a fuel-burning appliance or a storage garage, or
(b)contains a residential occupancy and is served by a forced-air fuel-burning appliance not contained within the building.
(2)Articles 6.9.3.3. and 6.9.3.4. apply to every building.
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OBC Div. B 6.9.3.2. Location of Carbon Monoxide Alarms
(1)A carbon monoxide alarm shall be installed in a suite of residential occupancy or care occupancy where
(a)a fuel-burning appliance or a flue is installed in the suite,
(b)a forced-air fuel-burning appliance provides heated air directly to the suite,
(c)a fuel-burning appliance or a flue is located in a room, suite or area that shares a common wall or floor or ceiling assembly with the suite, or
(d)a storage garage shares a common wall or floor or ceiling assembly with the suite.
(2)Where a carbon monoxide alarm is required by Sentence (1) to be installed in a suite of residential occupancy or care occupancy, other than a suite that consists of a combined living and sleeping area, a carbon monoxide alarm shall be installed
(a)adjacent to each sleeping room in the suite, and
(b)on each storey without a sleeping room in the suite.
(3)Where a carbon monoxide alarm is required by Sentence (1) to be installed in a suite of residential occupancy or care occupancy that consists of a combined living and sleeping area, a carbon monoxide alarm shall be installed in the combined living and sleeping area.
(4)In addition to the carbon monoxide alarms required to be installed in a suite of residential occupancy or care occupancy in accordance with Sentence (2), a carbon monoxide alarm shall be installed in each sleeping room within the suite where the sleeping room
(a)contains a fuel-burning appliance or a flue, or
(b)shares a common wall or floor or ceiling assembly with
(i)a room, suite or area that is located outside the suite and contains a fuel-burning appliance or a flue, or
(ii)a storage garage.
(5)Carbon monoxide alarms shall be installed in public corridors serving suites of residential occupancy where the corridor is directly heated by a forced-air fuel-burning appliance.
(6)Where carbon monoxide alarms are required by Sentence (5) to be installed in a public corridor, the carbon monoxide alarms shall be installed such that
(a)there is at least one carbon monoxide alarm in each portion of a divided corridor, and
(b)each carbon monoxide alarm in an undivided portion of a corridor is spaced not more than 25 m apart.
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OBC Div. B 6.9.3.3. Location of Carbon Monoxide Alarms in All Buildings
(1)A carbon monoxide alarm shall be installed in service rooms or other areas of a building where the service room or other area
(a)contains a fuel-burning appliance used for building services or laundry drying equipment, and
(b)is not located within a suite of residential occupancy.
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OBC Div. B 6.9.3.4. Installation and Conformance to Standards
(1)The carbon monoxide alarms required by Articles 6.9.3.2. and 6.9.3.3. shall
(a)except as permitted in Sentence (2), be permanently connected to an electrical circuit and shall have no disconnect switch between the overcurrent device and the carbon monoxide alarm,
(b)in case the regular power supply to the carbon monoxide alarm is interrupted, be provided with a battery as an alternative power source that can continue to provide power to the carbon monoxide alarm for a period of not less than 8 h in the standby condition, followed by the operation of the carbon monoxide alarm for an alarm signal for at least 12 h,
(c)be wired so that
(i)activation of one carbon monoxide alarm within a suite of residential occupancy will activate all carbon monoxide alarms within the suite, and
(ii)activation of one carbon monoxide alarm located in a public corridor serving suites of residential occupancy will activate all carbon monoxide alarms within the corridor,
(d)be audible within sleeping rooms when the intervening doors are closed, where located adjacent to a sleeping room in a suite of residential occupancy, and
(e)conform to
(i)CAN/CSA-6.19, "Residential Carbon Monoxide Alarming Devices", or
(ii)UL 2034, "Single and Multiple Station Carbon Monoxide Alarms".
(2)Where the building is not supplied with electrical power, carbon monoxide alarms are permitted to be battery operated.
(3)Except as permitted in Sentence (4), the carbon monoxide alarms required by Articles 6.9.4.2. and 6.9.4.3. shall have a visual signalling component conforming to the requirements in 18.5.3. (Light, Color and Pulse Characteristics) of NFPA 72, "National Fire Alarm and Signaling Code".
(4)Where the building is not supplied with electrical power, carbon monoxide alarms need not have a visual signalling component.
(5)The luminous intensity for visual signalling components required by Sentence (3) that are installed in sleeping rooms or combined living and sleeping areas shall be a minimum of 175 cd.
(6)The visual signalling component required by Sentence (3) need not
(a)be integrated with the carbon monoxide alarm provided it is interconnected to it,
(b)be on battery backup, or
(c)have synchronized flash rates, when installed in a dwelling unit.
(7)The carbon monoxide alarms required by Articles 6.9.3.2. and 6.9.3.3. shall be installed
(a)at the manufacturer's recommended height, or
(b)in the absence of specific instructions, on or near the ceiling.
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OBC Div. B 6.9.4.2. Fireplaces
(1)Fireplaces shall conform to the requirements of Section 9.22.
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