The Ontario Building Code | Required Sheathing Membrane and Installation
9.27.3.3. Required Sheathing Membrane and installation
(1) Except as provided in Articles 9.27.3.4. to 9.27.3.6., at least one layer of sheathing membrane shall be applied beneath siding, stucco or masonry veneer.
(2) Sheathing membrane required in Sentence (1) shall be applied so that joints are lapped not less than 100 mm.
(3) Where sheathing membrane required in Sentence (1) is applied horizontally, the upper sheets shall overlap the lower sheets.
In Plain Language
A sheathing membrane is required and must be installed as set out in this article, providing the water-resistive barrier behind the cladding.
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.