Code Library › Volume 1 › Section 9.20 — Masonry and Insulating Concrete Form
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.20.13.9.Protection of Interior Finish

(1) Except as provided in Sentence (3), where the interior finish of the exterior walls of a building is a type that may be damaged by moisture, exterior masonry walls, other than cavity walls or walls that are protected for their full height by a roof of a carport or porch, shall be (a) parged on the interior surface, and (b) covered with No. 15 breather-type asphalt-saturated paper conforming to CAN/CGSB-51.32-M, “Sheathing, Membrane, Breather Type,” and shall be lapped not less than 100 mm at the joints. (2) In situations described in Sentence (1), flashing shall be provided where water will accumulate, to lead it to the exterior. (3) Where insulation effectively limits the passage of water vapour and is applied by a waterproof adhesive or by mortar directly to the masonry, the requirements for sheathing paper do not apply. (See Note A-9.20.13.9.(3))
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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.