Part 9 ventilation, heating, air-conditioning and electrical (Building Services)

Last updated October 22, 2026

Values this chapter turns on

min kitchen supplemental exhaust fan capacity: 50 L/s; min kitchen supplemental exhaust fan capacity
min distance from intakes to contaminant sources: 1,800 mm; min distance from intakes to contaminant sources
unfinished basement area per lighting outlet: 30 m²; unfinished basement area per lighting outlet
duct system heat input above which Part 6 applies: 120 kW; duct system heat input above which Part 6 applies

This chapter covers the house-scale mechanical and electrical rules in Part 9: Section 9.32 (ventilation), Section 9.33 (heating and air-conditioning) and Section 9.34 (electrical facilities), plus a handful of related Articles on crawl spaces, chimneys, fireplaces, vapour barriers, hot water and change of use. Questions here are mostly quick lookups with numbers: litres per second, metres, millimetres and degrees. The skill being tested is knowing which Article holds the number and where Part 9 hands you over to Part 6.

Part 9 ventilation (Section 9.32)

Scope first. Section 9.32 applies only to rooms and spaces in residential occupancies; every other occupancy is ventilated under Part 6 OBC Div. B 9.32.1.1.. A storage garage for up to 4 vehicles serving a residential occupancy may be treated as part of it.

Two seasons. Every residential occupancy needs non-heating-season ventilation (natural or mechanical) and, where it has electrical power and a heating system, heating-season ventilation OBC Div. B 9.32.1.2..

Natural ventilation uses openable area from the natural ventilation table: for example 0.28 m² per finished room inside a dwelling unit and 0.09 m² for a bathroom OBC Div. B 9.32.2.2..
A room with no natural ventilation that is mechanically cooled uses air change rates (10 L/s for the master bedroom, 5 L/s for most other rooms); one that is not mechanically cooled needs one air change per hour OBC Div. B 9.32.2.3..

Heating-season system. Subsection 9.32.3. is a prescriptive path for dwelling units with 5 or fewer bedrooms; larger units, or any designer who prefers, use CAN/CSA-F326-M good practice or Part 6 OBC Div. B 9.32.3.1.. The prescriptive system has three parts: a principal ventilation fan, supplemental exhaust fans, and protection against depressurization.

Item	Key rule (paraphrased)	Article
Principal fan capacity	Read min and max from the principal fan table by bedroom count (3 bedrooms: 22 to 32 L/s)	9.32.3.3.
Principal fan switch	Manual switch in the living area, marked "ventilation fan"	9.32.3.3.(5)
Kitchen supplemental fan	At least 50 L/s, unless the principal fan intake is the only one and is in the kitchen, or a 2.5 times high-speed option is used	9.32.3.7.
Bathroom supplemental fan	At least 25 L/s where no principal fan intake serves that room	9.32.3.7.(4)
Outdoor air without forced air	Supply fan within ± 10% of principal exhaust; tempered to 12°C unless an HRV supplies it	9.32.3.5.
Make-up air	Required for exhaust devices where naturally vented fuel-fired heating or water heating exists	9.32.3.8.

Exhaust-only systems (no outdoor air supply) are allowed only where the unit has no solid-fuel appliance, no non-direct-vent fireplace and no naturally vented fuel-fired heater, and has a forced-air circulation fan rated at least 5 times the principal fan's exhaust capacity OBC Div. B 9.32.3.6..

Make-up air for an exhaust device must be supplied by a fan rated at not less than the device's exhaust capacity and not more than that plus 10% OBC Div. B 9.32.3.8.. It is not needed where a CAN/CGSB-51.71 depressurization test shows the appliances stay within limits, or for a radon subfloor depressurization fan.

Openings outdoors OBC Div. B 9.32.3.13.: an intake sits at least 450 mm above grade (or the expected snow depth, if greater); intakes are at least 1,800 mm from contaminant sources such as gas vents and oil fill pipes; moist-air exhaust outlets are at least 1,800 mm from intakes and vented soffits; an exhaust outlet is at least 100 mm above grade.

Carbon monoxide alarms also sit in this Subsection: required where a suite has a fuel-burning appliance or shares an assembly with a storage garage, adjacent to each sleeping room, hardwired with battery backup (8 h standby then 12 h alarm), interconnected within the suite OBC Div. B 9.32.3.9A. OBC Div. B 9.32.3.9C..

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Heating and air-conditioning systems (9.33.1 to 9.33.5)

Section 9.33 covers heating and cooling systems serving only one dwelling unit (and radiant systems in houses with a secondary suite). Anything else goes to Part 6 OBC Div. B 9.33.1.1..

Space	Minimum indoor design temperature
Living spaces	22°C
Unfinished basements	18°C
Common service rooms, ancillary spaces and exits in a house with a secondary suite	18°C
Heated crawl spaces	15°C

Source: OBC Div. B 9.33.3.1.. Outdoor design values come from SB-1 at the 2.5 percent criteria OBC Div. B 9.33.3.2.. Capacity is sized from a heat loss and gain calculation using good practice such as CSA F280, and over- or undersizing is judged under CSA F280 OBC Div. B 9.33.4.1. OBC Div. B 9.33.5.1.. Earth energy systems use CAN/CSA-C448.2 for houses and buildings up to 1,400 m² of conditioned space, and C448.1 above that OBC Div. B 9.33.5.2.. Solid-fuel appliances follow CSA B365 OBC Div. B 9.33.5.3..

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Ducts, piping, refrigeration and venting (9.33.6 to 9.33.10)

Rated input limit. A duct system with rated heat input over 120 kW falls out of Part 9 into Part 6 and Subsection 3.6.5. OBC Div. B 9.33.6.1..
Combustible ducts need Class 1 (CAN/ULC-S110), may not serve vertical runs of more than 2 storeys, and may not carry air above 120°C OBC Div. B 9.33.6.2..
Supply duct clearance depends on the plenum clearance. With a plenum clearance of 75 mm or less, keep the plenum clearance within 450 mm of the plenum and 12 mm beyond OBC Div. B 9.33.6.8..
Warm-air outlets: one per 40 m² of unfinished basement, one per 80 m² of heated crawl space, no more than 3 kW per outlet, supply air not over 70°C OBC Div. B 9.33.6.11..
Return air: no return inlet in a room that supplies combustion air to a furnace; one inlet per floor level OBC Div. B 9.33.6.12..
Pipe insulation in a service space: flame-spread rating not over 25 in noncombustible buildings and 75 in combustible ones; exposed pipe surfaces limited to 52°C OBC Div. B 9.33.8.2..
Pipe clearance from combustibles: none up to 95°C, 15 mm above 95°C up to 120°C, 25 mm above 120°C OBC Div. B Table 9.33.8.3..
Cooling coils with a fuel-fired furnace go in parallel, upstream (if the furnace allows it) or downstream (if the unit guards against excess temperature and pressure) OBC Div. B 9.33.9.1..
Venting of oil, gas and solid-fuel appliances follows the appliance installation standard; masonry chimneys go to Section 9.21 OBC Div. B 9.33.10.1..

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Electrical facilities (Section 9.34)

Where electrical service is available, every building gets the facilities in Section 9.34 OBC Div. B 9.34.1.2..

Location	Requirement
Each residential entrance	Exterior light switched from inside
Kitchens, bedrooms, bathrooms, hallways and similar rooms	Switched lighting outlet (a switched receptacle may replace it in bedrooms and living rooms)
Stairs with 4 or more risers in a dwelling unit	3-way switches at head and foot
Unfinished basement	One light per 30 m² or fraction; the one nearest the stairs switched at the head of the stairs
Garage or carport	Light switched near the doorway

Sources: OBC Div. B 9.34.2.1. to OBC Div. B 9.34.2.6.. Recessed fixtures may sit in insulated ceilings only if designed for it OBC Div. B 9.34.1.4.. Emergency lighting goes back to Subsection 9.9.12. OBC Div. B 9.34.3.1..

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Crawl spaces, chimneys, fireplaces and vapour barriers

A crawl space is treated as heated if it is a warm-air plenum, holds unsealed or uninsulated heating ducts or pipes, or is not separated from heated space OBC Div. B 9.18.1.3..
An unheated crawl space vented naturally needs 0.1 m² of vent for every 50 m² of floor area, on opposite sides OBC Div. B 9.18.3.1..
Only crawl spaces under 1-storey portions of a dwelling may be used as warm-air plenums; noncombustible cover extends 300 mm past a register OBC Div. B 9.18.7.1..
Section 9.21 covers masonry chimneys up to 12 m high serving appliances up to 120 kW total output; others go to Section 6.3 OBC Div. B 9.21.1.1..
Combustible material above a heat-circulating fireplace duct outlet: 300 mm if it projects 38 mm or more, 150 mm if less OBC Div. B 9.22.9.4..
The vapour barrier goes on the warm side OBC Div. B 9.25.4.3..
Service hot water to a dwelling unit is 45°C to 60°C; an electric storage tank is set to at least 60°C OBC Div. B 9.31.6.1A..
A change of use triggers compliance with Sections 9.31, 9.32 and 9.34 (among other listed Part 9 requirements) for the new occupancy OBC Div. B 9.41.2.1..

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Common traps

Using 9.32 for an office or shop. Non-residential occupancies always go to Part 6.
Taking the 9.32.3 prescriptive path for a 6-bedroom unit. It stops at 5 bedrooms.
Forgetting the make-up air range is a band: not less than the exhaust, not more than exhaust plus 10%.
Rounding down lighting outlets in a basement. "Or fraction thereof" means round up.
Treating 120 kW as a chimney height limit. It is a heat output (chimneys) or heat input (duct systems) limit; the chimney height limit is 12 m.

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
Part 9 ventilation (Section 9.32)	Exhaust-only systems (no outdoor air supply) are allowed only where the unit has no solid-fuel appliance, no non-direct-vent fireplace and no naturally vented fuel-fired heater…
Heating and air-conditioning systems (9.33.1 to 9.33.5)	Section 9.33 covers heating and cooling systems serving only one dwelling unit (and radiant systems in houses with a secondary suite).
Electrical facilities (Section 9.34)	Where electrical service is available, every building gets the facilities in Section 9.34.
Crawl spaces, chimneys, fireplaces and vapour barriers	A 160 m² unheated crawl space: 160 / 50 = 3.2, times 0.1 m² gives 0.32 m² of unobstructed vent area.

Part 9 ventilation (Section 9.32)
Exhaust-only systems (no outdoor air supply) are allowed only where the unit has no solid-fuel appliance, no non-direct-vent fireplace and no naturally vented fuel-fired heater…
Heating and air-conditioning systems (9.33.1 to 9.33.5)
Section 9.33 covers heating and cooling systems serving only one dwelling unit (and radiant systems in houses with a secondary suite).
Electrical facilities (Section 9.34)
Where electrical service is available, every building gets the facilities in Section 9.34.
Crawl spaces, chimneys, fireplaces and vapour barriers
A 160 m² unheated crawl space: 160 / 50 = 3.2, times 0.1 m² gives 0.32 m² of unobstructed vent area.

Usual exam traps

Using 9.32 for an office or shop. Non-residential occupancies always go to Part 6.
Taking the 9.32.3 prescriptive path for a 6-bedroom unit. It stops at 5 bedrooms.
Forgetting the make-up air range is a band: not less than the exhaust, not more than exhaust plus 10%.
Rounding down lighting outlets in a basement. "Or fraction thereof" means round up.
Treating 120 kW as a chimney height limit. It is a heat output (chimneys) or heat input (duct systems) limit; the chimney height limit is 12 m.

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Code cited in this chapter

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

OBC Div. B 9.32.1.1. Application
(1)This Section applies to the ventilation of rooms and spaces in residential occupancies.
(2)Ventilation of all other occupancies shall comply with Part 6.
(3)A storage garage for up to 4 motor vehicles that serves a residential occupancy may be considered to be part of that occupancy.
Open OBC Div. B 9.32.1.1. in the code viewer
OBC Div. B 9.32.1.2. Required Ventilation
(1)Every residential occupancy shall incorporate
(a)provisions for non-heating-season ventilation in accordance with Subsection 9.32.2., and
(b)except as required by Sentences (2) and (3), if supplied with electrical power and a heating system, provisions for heating-season ventilation in accordance with Part 6.
(2)A self-contained heating-season ventilation system serving a single dwelling unit shall comply with Subsection 9.32.3. (See Note A-9.32.1.2.(2))
(3)In houses that contain a secondary suite, heating-season ventilation need not be provided for
(a)exits,
(b)public corridors, and
(c)ancillary spaces that are not within a dwelling unit, except as provided in Sentence (4).
(See Note A-9.32.1.2.(2))
(4)Where ancillary spaces described in Clause (3)(c) contain exhaust devices, these spaces shall be provided with make-up air in accordance with Article 9.32.3.8.
Open OBC Div. B 9.32.1.2. in the code viewer
OBC Div. B 9.32.2.2. Non-Heating-Season Natural Ventilation
(1)The unobstructed openable ventilation area to the outdoors for rooms and spaces in residential buildings ventilated by natural means shall conform to Table 9.32.2.2.
(2)Where a vestibule opens directly off a living or dining room within a dwelling unit, ventilation to the outdoors for such rooms may be through the vestibule.
(3)Openings for natural ventilation other than windows shall provide protection from the weather and insects.
(4)Screening shall be of corrosion-resistant material.
Open OBC Div. B 9.32.2.2. in the code viewer
OBC Div. B 9.32.2.3. Non-Heating-Season Mechanical Ventilation
(1)Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is mechanically cooled, its non-heating-season mechanical ventilation system shall
(a)have the capacity to exhaust air from inside the room or space, or to introduce outdoor air into that room or space, at a rate conforming with Table 9.32.2.3., or
(b)comply with Subsection 9.32.3.
(2)In applying Clause (1)(a),
(a)at least one bedroom in each dwelling unit shall be designated as the master bedroom,
(b)air change rates for any combined living/dining or family/dining space shall be determined as if the spaces were individual rooms,
(c)where a basement incorporates rooms of the types designated in Table 9.32.2.3., the assigned air change rate for each room shall be as specified for those types of rooms,
(d)basement areas used for other purposes that exceed 2/3 of the total basement floor area shall be assigned an air change rate of 10 L/s,
(e)basement areas used for other purposes that are 2/3 of the total basement floor area or less shall be assigned an air change rate of 5 L/s, and
(f)other habitable rooms, other than spaces intended solely for access, egress, storage, or service equipment, shall be assigned an air change rate of 5 L/s.
(3)Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is not mechanically cooled, the non-heating-season mechanical ventilation system shall have the capacity to exhaust indoor air from the room or space or to introduce outdoor air to that room or space at a rate of one air change per hour.
(4)A non-heating-season mechanical ventilation system shall be designed and installed in conformance with good practice such as that described in the ASHRAE Handbooks and Standards, the HRAI Digest, the Hydronics Institute Manuals and the SMACNA Manuals.
Open OBC Div. B 9.32.2.3. in the code viewer
OBC Div. B 9.32.3.1. Required Ventilation
(1)The heating-season ventilation required by Clause 9.32.1.2.(1)(b) shall be provided by a mechanical ventilation system complying with
(a)good practice such as that described in CAN/CSA-F326-M, "Residential Mechanical Ventilation Systems,"
(b)for dwelling units with 5 or fewer bedrooms, the balance of this Subsection, or
(c)Part 6.
(2)Mechanical ventilation systems complying with the balance of this Subsection shall incorporate at least the following components:
(a)a principal ventilation system complying with Article 9.32.3.3.,
(b)supplemental exhaust fans complying with Article 9.32.3.7., and
(c)protection against depressurization in accordance with Article 9.32.3.8.
Open OBC Div. B 9.32.3.1. in the code viewer
OBC Div. B 9.32.3.6. Exhaust-Only Ventilation Systems
(1)A ventilation system with no provision for the introduction of outdoor air to the dwelling unit may only be used where the dwelling unit
(a)contains no solid-fuel-burning appliance, no fireplace of other than direct-vented type, and no other fuel-fired space- or water-heating appliance of other than direct-vented or mechanically vented types, and
(b)has a forced air distribution system with a circulation fan with a rated capacity equal to at least 5 times the actual normal operating exhaust capacity of the fan installed to satisfy the requirement for a principal ventilation fan, a supply side that complies with Sentences 9.32.3.5.(10) to (12), and a return side that complies with Articles 9.33.6.12. and 9.33.6.13.
(2)Except as provided in Sentence (3), where an exhaust-only system is installed, the principal ventilation fan control required by Sentence 9.32.3.3.(5) shall be wired in such a way that, where applicable, activation of the principal ventilation fan automatically activates the circulation fan of the forced air distribution system required by Clause (1)(b) at its rated capacity.
(3)Interlocking the forced air distribution system's circulation fan with the principal ventilation fan as required by Sentence (2) is not required where the forced air distribution system is equipped with a control that automatically activates the circulation fan at user-selected intervals.
Open OBC Div. B 9.32.3.6. in the code viewer
OBC Div. B 9.32.3.8. Protection Against Depressurization
(1)This Article applies to
(a)dwelling units that contain a fuel-fired space-heating appliance or fuel-fired water-heating appliance of other than direct-vented or mechanically vented types, and
(b)ancillary spaces that contain an exhaust device, where the space is not within a dwelling unit in a house with a secondary suite and where the house with a secondary suite contains a fuel-fired space-heating appliance or fuel-fired water-heating appliance of other than direct-vented or mechanically vented types.
(2)Except as provided in Sentences (6) to (8), any mechanical air exhausting device, other than the principal ventilation fan operating at a rate not greater than the maximum permitted by Table 9.32.3.3., shall be provided with outdoor make-up air supplied by a fan rated to deliver outdoor air to the dwelling unit at a rate
(a)not less than the exhaust capacity of the device, and
(b)not greater than that exhaust capacity plus 10%.
(3)An outdoor make-up air supply fan required by Sentence (2) shall be wired so that it is activated whenever the device for which it supplies outdoor make-up air is activated.
(4)The outdoor make-up air required by Sentence (2) shall be
(a)introduced to a normally unoccupied area in the dwelling unit, or
(b)tempered to at least 12°C before being introduced to occupied areas or to a supply duct system.
(5)If the outdoor make-up air required by Sentence (2) is not tempered upstream of the supply fan, the supply fan required by Sentence (2) shall be approved by the manufacturer for the handling of untempered outdoor air.
(6)The provision of make-up air as described in Sentence (2) is not required in a dwelling unit with solid-fuel-burning appliances, where all other fuel-fired appliances are direct-vented or mechanically vented.
(7)The provision of make-up air as described in Sentence (2) is not required if it can be shown using the test procedures in CAN/CGSB-51.71, "Depressurization Test," that the maximum depressurization levels to which fuel-fired space- or water-heating appliances and their venting systems will be exposed will not exceed the limits set out in CAN/CGSB-51.71 for the categories of fuel-fired appliances and venting systems installed in the dwelling unit.
(8)The provision of make-up air as described in Sentence (2) is not required for mechanical exhausting devices operating a subfloor depressurization system installed for the purpose of reducing the risk of radon ingress.
Open OBC Div. B 9.32.3.8. in the code viewer
OBC Div. B 9.32.3.13. Outdoor Intake and Exhaust Openings
(1)Intake openings shall be located so as to avoid contamination of the ventilation air from other local sources such as automobile exhaust and exhaust from the building or adjacent buildings.
(2)The distance from the bottom of an air intake opening to finished ground or to any nearer and lower permanent horizontal surface shall be not less than 450 mm or the depth of expected snow accumulation, whichever is greater.
(3)The distance separating air intakes for mechanical ventilation from exhaust outlets that are potential sources of contaminants, such as gas vents or oil fill pipes, shall be not less than 1,800 mm.
(4)Except as provided in Sentences (5) and (6), exhaust outlets that discharge air containing moisture, such as bathroom ventilation and clothes dryer exhaust outlets, shall be located at least 1,800 mm from air intakes and vented soffits.
(5)Where an exhaust outlet referred to in Sentence (4) is located within a soffit, the soffit shall either be unvented, or if vented, the full depth of the soffit shall be blocked for a distance of 1,800 mm on each side of the exhaust outlet.
(6)Where an exhaust outlet referred to in Sentence (4) is located in a side wall less than 1,800 mm from a soffit, a section of the soffit above the exhaust outlet shall be unvented, or if vented, the full depth of the soffit shall be blocked in accordance with the widths stipulated in Table 9.32.3.13.-A, centred over the location of the outlet.
(7)Air intakes shall be clearly labeled as such for identification from locations outside the dwelling unit.
(8)The distance from the bottom of an exhaust outlet to finished ground or to any nearer and lower permanent horizontal surface shall be not less than 100 mm.
(9)Where air intake and exhaust openings are in exposed locations, provision shall be made to protect them from the entry of precipitation by the use of louvres, weather cowls or other suitable protection.
(10)Air intake openings shall incorporate screens or grilles to protect against the entry of animals and insects.
(11)Except for exhaust outlets serving heat recovery ventilators, exhaust outlets shall incorporate backdraft dampers.
(12)An exhaust outlet that does not incorporate a backdraft damper located at the building envelope shall incorporate a screen located at the building envelope to protect against the entry of animals.
(13)Screens, grilles and filters installed in air intake and exhaust openings shall be easily removable for cleaning purposes, without the need for special tools.
(14)Where screens or grilles are installed in air intake and exhaust openings, the net free area of the air intake or exhaust opening shall be equal to or greater than the required cross-sectional area of the duct served or such openings shall comply with Table 9.32.3.13.-B.
(15)Screens and grilles shall be of corrosion-resistant material.
Open OBC Div. B 9.32.3.13. in the code viewer

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OBC Div. B 9.32.3.9A. Location of Carbon Monoxide Alarms
(1)A carbon monoxide alarm shall be installed in a suite of supply duct 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, 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 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 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
(i)with a room, suite or area that is located outside the suite and contains a fuel-burning appliance or a flue,
(ii)with a storage garage, or
(iii)that is adjacent to an attic or crawl space to which the storage garage is also adjacent.
(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.
Open OBC Div. B 9.32.3.9A. in the code viewer
OBC Div. B 9.32.3.9C. Installation and Conformance to Standards
(1)The carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. 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,
(ii)activation of one carbon monoxide alarm within a house with a secondary suite will activate all carbon monoxide alarms within the house with a secondary suite including their common spaces, and
(iii)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
(a)are permitted to be battery operated, and
(b)need not have a visual signaling component.
(3)Except as permitted in Sentence (2), the carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. 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)The luminous intensity for visual signaling components required by Sentence (3) that are installed in sleeping rooms or combined living and sleeping areas shall be a minimum of 175 cd.
(5)The visual signaling 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.
(6)The carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. shall be installed
(a)at the manufacturer's recommended height, or
(b)in the absence of specific instructions, on or near the ceiling.
Open OBC Div. B 9.32.3.9C. in the code viewer
OBC Div. B 9.33.1.1. Application
(1)This Section applies to the design and installation of
(a)heating systems, including requirements for combustion air, and air-conditioning systems serving only one dwelling unit, and
(b)radiant heating systems in houses with a secondary suite including their common spaces.
(2)The design and installation of heating systems, including requirements for combustion air, and air-conditioning systems other than those described in Sentence (1) shall conform to Part 6. (See Note A-9.33.1.1.(2) and Subsection 9.10.10.)
(2.1)Repairs or component replacements that change the capacity or extent of safety of an existing heating, ventilating or air-conditioning system and that alter the method of operation shall conform to this Code.
(3)Air duct distribution systems serving one of the dwelling units in a house with a secondary suite shall not be directly interconnected with other parts of the house.
Open OBC Div. B 9.33.1.1. in the code viewer
OBC Div. B 9.33.3.1. Indoor Design Temperatures
(1)At the outside design temperature, required heating facilities shall be capable of maintaining an indoor air temperature of not less than
(a)22°C in all living spaces,
(b)18°C in unfinished basements,
(c)18°C in common service rooms, ancillary spaces and exits in houses with a secondary suite, and
(d)15°C in heated crawl spaces.
Open OBC Div. B 9.33.3.1. in the code viewer
OBC Div. B 9.33.3.2. Outdoor Design Temperatures
(1)The outdoor conditions to be used in designing heating, ventilating and air-conditioning systems shall be the appropriate values for the location as set out in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," using 2.5 percent design temperature criteria.
Open OBC Div. B 9.33.3.2. in the code viewer
OBC Div. B 9.33.4.1. Design of Heating and Air-Conditioning Systems
(1)Heating, ventilating and air-conditioning systems, including related mechanical refrigeration systems, shall be designed, constructed and installed to conform to good engineering practice appropriate to the circumstances such as described in
(a)the ASHRAE Handbooks and Standards,
(b)CSA F280, "Determining the required capacity of residential space heating and cooling appliances," and the outside winter design temperatures shall conform to MMAH Supplementary Standard SB-1, "Climatic and Seismic Data,"
(c)CAN/CSA-F326-M, "Residential Mechanical Ventilation Systems,"
(d)the NFPA Standards,
(e)the HRAI Digest,
(f)the Hydronics Institute Manuals, and
(g)the SMACNA Manuals. (See also Subsection 9.32.3. for the design of systems that also provide ventilation.)
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OBC Div. B 9.33.5.1. Capacity of Heating Appliances
(1)The heating system capacity shall be based on the heating load calculated in accordance with Sentence 9.33.4.1.(1).
(2)Where a cooling system is installed, the cooling system capacity shall be based on the cooling load calculated in accordance with Sentence 9.33.4.1.(1).
(3)The oversizing and undersizing of heating and cooling equipment capacities shall be determined in accordance with the requirements of CSA F280, "Determining the required capacity of residential space heating and cooling appliances."
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OBC Div. B 9.33.5.2. Installation Standards (See also Article 9.33.5.3.)
(1)The design and installation of earth energy systems shall conform to CAN/CSA-C448.2, "Design and installation of earth energy systems for residential and other small buildings," where such systems use groundwater, submerged heat exchangers or ground heat exchangers to serve,
(a)a house with or without a secondary unit, or,
(b)a building, other than a house with or without a secondary unit, where the conditioned space is not more than 1,400 m².
(2)Except for a house with or without a secondary unit, the design and installation of earth energy systems shall conform to CAN/CSA-C448.1, "Design and installation of earth energy systems for commercial and institutional buildings," where such systems use groundwater, submerged heat exchangers or ground heat exchangers to condition a floor space area more than 1,400 m².
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OBC Div. B 9.33.5.3. Design, Construction and Installation Standard for Solid-Fuel-Burning Appliances
(1)The design, construction and installation, including the provision of combustion air, of solid-fuel-burning appliances and equipment, including stoves, cooktops, ovens and space heaters, shall conform to CSA B365, "Installation Code for Solid-Fuel-Burning Appliances and Equipment." (See Note A-9.33.5.3.(1))
(2)Solid fuel-burning stoves, furnaces and hydronic heating systems designed to burn solid fuels, other than coal, shall conform to the particulate emission limits of,
(a)CSA B415.1, "Performance Testing of Solid-Fuel-Burning Heating Appliances", or
(b)the "Standards of Performance for New Residential Wood Heaters", set out in Subpart AAA of Part 60 of Title 40 of the Code of Federal Regulations, published by the United States Environmental Protection Agency, as it read on March 16, 2015. (See Note A-9.33.5.3.(2))
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OBC Div. B 9.33.6.1. Application
(1)The requirements of this Subsection apply to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems that serve an individual dwelling unit within the scope of Part 9.
(2)Air duct distribution systems in which the rated heat input exceeds 120 kW shall conform to Part 6 and Subsection 3.6.5.
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OBC Div. B 9.33.6.2. Materials in Air Duct Systems
(1)Except as provided in Sentences (2) to (6.2) and in Article 3.6.4.3., all ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of steel, aluminum alloy, copper, clay or similar noncombustible material.
(2)Ducts, associated fittings and plenums are permitted to contain combustible material provided they
(a)conform to the appropriate requirements for Class 1 duct materials in CAN/ULC-S110, "Standard Methods of Test for Air Ducts,"
(b)conform to Article 3.1.5.18. and Subsection 3.1.9.,
(c)are not used in vertical runs serving more than 2 storeys, and
(d)are not used in air duct systems in which the air temperature may exceed 120°C.
(3)Duct sealants shall have a flame-spread rating of not more than 25 and a smoke developed classification of not more than 50.
(4)Duct connectors that contain combustible materials and that are used between ducts and air outlet units shall
(a)conform to the appropriate requirements for Class 1 air duct materials in CAN/ULC-S110, "Standard Methods of Test for Air Ducts,"
(b)be limited to 4 m in length,
(c)be used only in horizontal runs, and
(d)not penetrate required fire separations.
(5)Combustibleducts that are part of a duct system carrying only ventilation air and that are contained entirely within a dwelling unit need not comply with the requirements of Sentences (1) to (4).
(6)Except as provided in Sentences 9.33.6.13.(2) and (3), ducts that are part of a return-air duct system and that are contained entirely within a dwelling unit need not comply with the requirements of Sentences (1) to (4).
(6.1)All ductwork and fittings shall be constructed and installed in conformance with SMACNA Manuals and ASHRAE Handbooks.
(6.2)All duct materials and fittings shall be
(a)suitable for exposure to the temperature and humidity of the air being conveyed, and
(b)resistant to corrosion due to contaminants in the air being conveyed in the duct.
(7)Materials referred to in Sentences (1) to (6.2), when used in a location where they may be subjected to excessive moisture, shall
(a)have no appreciable loss of strength when wet, and
(b)be corrosion-resistant.
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OBC Div. B 9.33.6.8. Clearances of Ducts and Plenums
(1)Reserved.
(2)Where the plenum clearance is 75 mm or less, the clearance between a supply duct and combustible material shall
(a)be equal to the required plenum clearance within 450 mm of the plenum, and
(b)be not less than 12 mm at a distance of 450 mm or more from the plenum, except that this clearance may be reduced to zero beyond a bend or offset in the duct sufficiently large to shield the remainder of the supply duct from direct radiation from the furnace heat exchanger. (See Note A-3.6.5.6.(2))
(3)Where the plenum clearance is more than 75 mm but not more than 150 mm, the clearance between a supply duct and combustible material shall be
(a)equal to the required plenum clearance within a horizontal distance of 1.8 m of the plenum, and
(b)not less than 12 mm at a horizontal distance of 1.8 m or more from the plenum, except that this distance may be reduced to zero beyond a bend or offset in the duct sufficiently large to shield the remainder of the duct from direct radiation from the furnace heat exchanger. (See Note A-3.6.5.6.(3))
(4)Where the plenum clearance is more than 150 mm, the clearance between a supply duct and combustible material shall be
(a)equal to the required plenum clearance within a horizontal distance of 1 m of the plenum,
(b)not less than 150 mm within a horizontal distance between 1 m and 1.8 m from the plenum, and
(c)not less than 25 mm at a horizontal distance of 1.8 m or more from the plenum, except that this distance may be reduced to 8 mm beyond a bend or offset in the duct sufficiently large to shield the remainder of the supply duct from direct radiation from the furnace heat exchanger. (See Note A-3.6.5.6.(4))
(5)Where a register is installed in a floor directly over a pipeless furnace, a double-walled register box with not less than 100 mm between walls, or a register box with the warm-air passage completely surrounded by the cold-air passage, shall be permitted in lieu of the clearances listed in Sentences (2) to (4).
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OBC Div. B 9.33.6.11. Warm-Air Supply Outlets
(1)In a dwelling unit, a warm-air supply outlet shall be provided in each finished room that is located adjacent to unheated space.
(2)Except as provided in Sentence (3), when a room described in Sentence (1) is located adjacent to exterior walls, such outlet shall be located so as to bathe at least one exterior wall or window with warm air, except in bathrooms, utility rooms or kitchens, where this may not be practical.
(3)Where the heating system is also designed to provide ventilation air, ceiling outlets or outlets located high on interior walls are permitted to be installed, provided the outlets are designed for this purpose and are installed with diffusers.
(4)At least one warm-air supply outlet shall be provided for each 40 m² of floor surface area in unfinished basements serving dwelling units, and it shall be located so as to provide adequate distribution of warm air throughout the basement.
(5)At least one warm-air supply outlet shall be provided for each 80 m² of floor surface area in heated crawl spaces serving dwelling units, and it shall be located so as to provide adequate distribution of warm air throughout the crawl space.
(6)Except for pipeless furnaces and floor furnaces, the capacity of warm-air supply outlets serving dwelling units shall be not less than the design heat loss from the area served and shall not exceed 3 kW per outlet.
(7)In basements and heated crawl spaces, the calculated heat gain from the supply ducts and plenum surfaces is permitted to be considered in calculating the design heat loss.
(8)The temperature of supply air at warm-air supply outlets shall not exceed 70°C.
(9)Warm-air supply outlets located in finished areas shall be provided with diffusers and adjustable openings and shall not be located on a furnace plenum.
(10)Air duct systems serving storage garages shall not be interconnected with other parts of the building.
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OBC Div. B 9.33.6.12. Return-Air Inlets
(1)Return-air inlets shall not be installed in an enclosed room or crawl space that provides combustion air to a furnace.
(2)Except for floor levels which are less than 900 mm above or below an adjacent floor level which is provided with a return-air inlet, at least one return-air inlet shall be provided in each floor level in a dwelling unit.
(3)Provision shall be made for the return of air from all rooms by leaving gaps beneath doors, using louvred doors or installing return duct inlets.
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OBC Div. B 9.33.8.2. Insulation and Coverings
(1)Insulation and coverings on pipes shall be composed of material suitable for the operating temperature of the system to withstand deterioration from softening, melting, mildew and mould.
(2)Insulation and coverings on pipes in which the temperature of the fluid exceeds 120°C
(a)shall be made of noncombustible material, or
(b)shall not flame, glow, smoulder or smoke when tested in accordance with ASTM C411, "Standard Specification for Hot-Surface Performance of High-Temperature Thermal Insulation," at the maximum temperature to which such insulation or covering is to be exposed in service.
(3)Except as provided in Sentence (6), where combustible insulation is used on piping in a horizontal or vertical service space, the insulation and coverings on such pipes shall have a flame-spread rating throughout the material of not more than
(a)25 in buildings of noncombustible construction, and
(b)75 in buildings of combustible construction.
(4)Except as provided in Sentence (6), insulation and coverings on piping located in rooms and spaces other than the service spaces described in Sentence (3) shall have a flame-spread rating not more than that required for the interior finish for the ceiling of the room or space.
(5)Pipes that are exposed to human contact shall be insulated so that the exposed surface does not exceed 52°C. (See Note A-6.5.1.1.(3))
(6)No flame-spread rating or smoke developed classification limitations are required where combustible insulation and coverings are used on piping when such piping is
(a)located within a concealed space in a wall,
(b)located in a floor slab, or
(c)enclosed in a noncombustible raceway or conduit.
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OBC Div. B Table 9.33.8.3. Clearance Between Steam or Hot Water Pipes and Combustible Material - Forming Part of Sentence 9.33.8.3.(1)
Table 9.33.8.3. Clearance Between Steam or Hot Water Pipes and Combustible Material - Forming Part of Sentence 9.33.8.3.(1) Forming Part of Sentence 9.33.8.3.(1) Steam or Water Temperature (T), °C | Minimum Clearance, mm T ≤ 95 | No clearance required. 95 < T ≤ 120 | 15 T > 120 | 25
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OBC Div. B 9.33.9.1. Cooling Units
(1)Where a cooling unit is combined with a fuel-fired furnace in the same duct system, the cooling unit shall be installed
(a)in parallel with the heating furnace,
(b)upstream of the furnace, provided the furnace is designed for such application, or
(c)downstream of the furnace, provided the cooling unit is designed to prevent excessive temperature or pressure in the refrigeration system.
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OBC Div. B 9.33.10.1. Requirement for Venting
(1)Except as provided in Articles 9.33.10.2. and 9.33.10.3., the products of combustion from oil-, gas- and solid-fuel-burning appliances, including stoves, cooktops, ovens and space heaters, shall be vented in conformance with the applicable appliance installation standard listed in Sentences 9.33.5.2.(1) and 9.33.5.3.(1).
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OBC Div. B 9.34.1.2. Required Facilities
(1)Where electrical services are available, electrical facilities shall be provided for every building in conformance with this Section.
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OBC Div. B 9.34.2.1. Lighting of Entrances
(1)An exterior lighting outlet with fixture controlled by a wall switch located within the building shall be provided at every entrance to buildings of residential occupancy.
(2)The exterior lighting outlet with fixture required by Sentence (1) may be controlled by a wall switch or panel accessible to authorized personnel only, where it serves,
(a)a building entrance serving multiple suites of residential occupancy,
(b)multiple dwelling unit entrances,
(c)hotels, or
(d)motels.
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OBC Div. B 9.34.2.6. Garages and Carports
(1)A lighting outlet with fixture shall be provided for an attached, built-in or detached garage or carport.
(2)Except as provided in Sentence (3), outlets required in Sentence (1) shall be controlled by a wall switch near the doorway.
(3)Where the outlet and fixture required in Sentence (1) are ceiling mounted above an area not normally occupied by a parked car, or are wall mounted, a fixture with a built-in switch is permitted to be used.
(4)Where a carport is lighted by a light at the entrance to a dwelling unit, additional carport lighting is not required.
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OBC Div. B 9.34.1.4. Recessed Lighting Fixtures
(1)Recessed lighting fixtures shall not be located in insulated ceilings unless the fixtures are designed for such installations.
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OBC Div. B 9.34.3.1. Criteria for Emergency Lighting
(1)Emergency lighting shall conform to Subsection 9.9.12.
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OBC Div. B 9.18.1.3. Heated and Unheated Crawl Spaces
(1)Crawl spaces shall be considered to be heated where the space
(a)is used as a warm air plenum,
(b)contains heating ducts or heating pipes that are not sealed and insulated to minimize heat loss to the space, or
(c)is not separated from heated space in accordance with Section 9.25.
(2)Heating of heated crawl spaces shall conform to Section 9.33.
(3)Insulation, an air barrier system and a vapour barrier shall be installed in the walls of heated crawl spaces in accordance with Section 9.25.
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OBC Div. B 9.18.3.1. Ventilation of Unheated Crawl Spaces
(1)Unheated crawl spaces shall be ventilated by natural or mechanical means.
(2)Where an unheated crawl space is ventilated by natural means, ventilation shall be provided to the outside air by not less than 0.1 m² of unobstructed vent area for every 50 m² of floor area.
(3)Vents shall be
(a)uniformly distributed on opposite sides of the building, and
(b)designed to prevent the entry of snow, rain and insects.
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OBC Div. B 9.18.7.1. Crawl Spaces as Warm Air Plenums
(1)Only crawl spaces under 1-storey portions of dwelling units shall be used as warm air plenums.
(2)Enclosing material in crawl spaces described in Sentence (1), including insulation, shall have a surface flame-spread rating not greater than 150.
(3)Combustible ground cover used as enclosing material in Sentence (2) shall be covered with noncombustible material. (See Note A-9.18.7.1.(3) and (4))
(4)Noncombustible material described in Sentence (3) shall
(a)extend not less than 300 mm beyond the projection of a register opening, and
(b)have turned-up edges. (See Note A-9.18.7.1.(3) and (4))
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OBC Div. B 9.21.1.1. Application
(1)This Section applies to,
(a)rectangular masonry or concrete chimneys not more than 12 m in height serving fireplaces or serving appliances having a combined total rated heat output of 120 kW or less, and
(b)flue pipes serving solid fuel-burning appliances.
(2)Reserved.
(3)Except as provided in Sentence 9.21.1.3.(1), chimneys (other than those described in Sentence (1) and Sentence 9.21.1.2.(1)), gas vents and flue pipes serving gas-, oil- or solid fuel-burning appliances and associated equipment shall conform to Section 6.3.
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OBC Div. B 9.22.9.4. Heat Circulating Duct Outlets
(1)The clearance of combustible material above heat-circulating duct outlets from those outlets shall be not less than
(a)300 mm where the combustible material projects not less than 38 mm from the face, and
(b)150 mm where the projection is less than 38 mm.
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OBC Div. B 9.25.4.3. Installation of Vapour Barriers
(1)Products installed to function as the vapour barrier shall protect the warm side of wall, ceiling and floor assemblies.
(2)Where different products are used for the vapour barrier and the insulation, the vapour barrier shall be installed sufficiently close to the warm side of the insulation to prevent condensation at design conditions. (See Note A-9.25.4.3.(2) and A-9.25.5.1.(1))
(3)Where the same product is used for the vapour barrier and the insulation, the product shall be installed sufficiently close to the warm side of the assembly to prevent condensation at design conditions. (See Note A-9.25.4.3.(2) , A-9.25.5.1.(1) and A-9.25.5.2.)
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OBC Div. B 9.31.6.1A. Hot Water Temperature
(1)Where a hot water supply is required by Article 9.31.4.3., equipment shall be installed to provide to every dwelling unit an adequate supply of service hot water with a temperature range from 45°C to 60°C.
(2)An electric storage-type service water heater shall have a minimum set storage temperature of 60°C.
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OBC Div. B 9.41.2.1. Change of Use and Compensating Construction
(1)Where proposed construction will result in a change of use described in Clauses 9.40.1.1.(1)(a) to (f), additional construction shall be required in order that the building or part of a building subject to the change of use conforms to the requirements of Subsections 9.5.1. and 9.5.3. to 9.5.10., Section 9.6., Article 9.7.2.3. Sentences 9.7.5.1.(2) and 9.7.6.2.(1) and (3), Articles 9.8.8.1. and 9.9.10.1., Subsection 9.10.17. and Sections 9.31., 9.32. and 9.34. as they apply to the new major occupancy that the building or part of a building is to support.
(2)For the purposes of this Article, existing buildings shall be classified as to their construction and occupancy as provided for in Sentence 11.2.1.1.(1).
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