The Ontario Building Code | Ground Cover in Unheated Crawl Spaces
9.18.6.1. Ground Cover in Unheated Crawl Spaces
(1) Where a crawl space is unheated, a ground cover shall be provided consisting of not less than,
(a) 50 mm of asphalt paving material,
(b) 100 mm of 15 MPa Portland cement concrete,
(c) Type S roll roofing, or
(d) 0.10 mm polyethylene.
(2) Joints in sheet-type ground cover required in Sentence (1) shall be lapped not less than 100 mm and weighted down.
In Plain Language
Unheated crawl spaces need ground cover, typically a vapour barrier laid over the soil, as set out in this article, reducing moisture migration from the ground into the space.
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.