The Ontario Building Code | Supply, Return, Intake and Exhaust Air Openings
6.2.3.12. Supply, Return, Intake and Exhaust Air openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings
(1) Supply, return and exhaust air openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings located less than 2 000 mm above the floor in rooms or spaces in buildings shall be protected by grilles having openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings of a size that will not allow the passage of a 15 mm diameter sphere.
(2) outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">door air intakes and exhaust outlets on the exterior of buildings shall be designed or located so that the air entering the buildingsystem will not contain more contaminants than the normal exterior air of the locality in which the building is situated.
(3) 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 avoid icing over of the screen openings.
(4) Screens required in Sentence (3) shall be accessible for maintenance.
(5) Combustible grilles, diffusers and other devices for supply, return and exhaust air openings in rooms shall conform to the flame-spread rating and smoke developed classification requirements for the interior finish of the surface on which they are installed.
In Plain Language
Supply, return, intake, and exhaust air openings must meet specific location and configuration requirements, preventing issues like exhaust air being drawn back into fresh air intakes.
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.