PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code
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9.32.3.3.Principal Ventilation System (See Note A-9.32.3.3.)
(1) The principal ventilation system shall incorporate the following components:
(a) a principal ventilation fan complying with this Article, and
(b) except as permitted by Article 9.32.3.6., provision for the introduction of outdoor air to the dwelling unit, in
conformance with Article 9.32.3.4. or 9.32.3.5.
(2) The principal ventilation fan shall be capable of operating at an exhaust capacity complying with Table 9.32.3.3.,
referred to hereinafter as the “normal operating exhaust capacity.” (See Note A-9.32.3.3.(2))
Table 9.32.3.3.
Normal Operating Exhaust Capacity of Principal Ventilation Fan
Forming Part of Sentence 9.32.3.3.(2)
Normal Operating Exhaust Capacity of Principal Ventilation Fan, L/s
Number of Bedrooms in Dwelling Unit
Minimum Maximum
1 16 24
2 18 28
3 22 32
4 26 38
5 30 45
More than 5 System must comply with Clause 9.32.3.1.(1)(a)
(3) The requirement for a principal ventilation fan may be satisfied by a single fan, by the exhaust side of a heat
recovery ventilator, or by a group of fans, provided all fans in the group are controlled simultaneously by a controller
complying with Sentences (5) to (7). (See Note A-9.32.3.3.(3))
(4) The components of the principal ventilation system shall be approved by their manufacturer for continuous
operation.
(5) The principal ventilation fan shall be controlled by a manual switch located within the living area of the dwelling
unit and clearly marked VENTILATION FAN. (See Note A-9.32.3.3.(5))
(6) If all controls serving the principal ventilation fan are in the “off” position, the principal ventilation system shall not
operate.
(7) The requirement for a manual switch stated in Sentence (5) can be satisfied by a manual override incorporated in a
dehumidistat or other automatic control, provided
(a) the automatic control is located within the living area of the dwelling unit, and
(b) the manual override is clearly marked VENTILATION FAN.
(8) Where the principal ventilation fan is controlled by a dehumidistat or other automatic control in addition to the
manual switch required by Sentence (5), the manual switch shall be capable of activating the fan regardless of the setting
of the automatic control.
(9) Where an exhaust air intake for the principal ventilation fan is connected directly to the return side of the duct
system of a forced air heating system or other forced air distribution system, it shall be connected, where applicable,
not less than 1 m upstream from the connection of the outdoor air supply duct required by Sentence 9.32.3.4.(5).
(10) Exhaust air intakes for principal ventilation fans located in kitchens, bathrooms and water-closet rooms shall be
located in the ceiling or on the wall not less than 2 m above the floor. (See Note A-9.32.3.3.(10))
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.