Code Library › Volume 1 › Section 9.25 — Heat Transfer, Air Leakage and
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.25.1.1.Scope and Application

(1) This Section is concerned with heat, air and water vapour transfer and measures to control condensation. (2) All walls, ceilings and floors separating conditioned space from unconditioned space, the exterior air or the ground shall be (a) provided with (i) thermal insulation conforming to Subsection 9.25.2., (ii) an air barrier system conforming to Subsection 9.25.3., and (iii) a vapour barrier conforming to Subsection 9.25.4., and (b) constructed in such a way that the properties and relative position of all materials conform to Subsection 9.25.5. (See Note A-9.25.1.1.(2)) (3) Insulation and sealing of heating and ventilating ducts shall conform to Sections 9.32., 9.33.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.