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

9.25.3.1.Required Barrier to Air Leakage

(1) Wall, ceiling and floor assemblies that separate conditioned space from unconditioned space or from the ground shall be constructed so as to include an air barrier system that will provide a continuous barrier to air leakage (a) from the interior of the building into wall, floor, attic or roof spaces sufficient to prevent excessive moisture condensation in such spaces during the winter, and (b) from the exterior or the ground inward sufficient to (i) prevent moisture condensation on the room side during winter, (ii) ensure comfortable conditions for the occupants, and (iii) minimize the ingress of soil gas. (See Note A-9.25.3.1.(1)) (2) The continuity of the air barrier system shall extend throughout the basement.
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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.