The Ontario Building Code | Protection from Dampness
9.23.2.3. Protection from Dampness
(1) Except as permitted in Sentence (2), wood framing members that are not pressure-treated with a wood preservative and that are supported on concrete in contact with the ground or fill shall be separated from the concrete by not less than 0.05 mm polyethylene film or Type S roll roofing.
(2) Dampproofing material referred to in Sentence (1) is not required where the wood member is at least 150 mm above the ground.
In Plain Language
Wood framing must be protected from dampness as set out in this article, working alongside the decay protection requirement to keep framing dry and sound.
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.