The Ontario Building Code | Crawl Spaces and Attic or Roof Spaces
6.2.2.7. Crawl Spaces and attic or Roof Spaces
(1) Every crawl space and every attic or roof spaceshall be ventilated by natural or mechanical means.
6.2.3. Air Duct Systems
In Plain Language
Every crawl space and every attic or roof space must be ventilated by natural or mechanical means, controlling moisture buildup that could otherwise lead to decay or mould in these often-hidden building spaces.
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.