The Ontario Building Code | Make-up Air
6.2.4.12. Make-up Air
(1) In ventilating systems that exhaust air to the outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">doors, provision shall be made for the admission of a supply of make-up air in sufficient quantity so that the operation of the exhaust system and other exhaust equipment or combustion equipment is not adversely affected.
In Plain Language
Residential ventilating systems that exhaust air outdoors must provide for adequate make-up air supply, mirroring the general make-up air requirement but scaled to residential system needs.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.