The Ontario Building Code | Protection of Interior Finish 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 wallsor 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 the insulation" title ="Toronto home insulation">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.