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.
Article 9.27.3.4. Ontario Regulation 332/12 Building Code, Information published by oncodes.ca for educational purposes only.
Sheathing membranes are used in exterior wall assemblies as a key environmental separator. They usually extend beyond the structural sheathing in order to provide lower-air leakage performance and greater water vapor transmission resistance than do ordinary weatherstripping materials (such as Tyvek® and Phenolic Foam®). Sheathing membranes can be made with different materials, like: polyisocyanurate (polyiso), polyethylene, polyvinyl chloride (PVC), expanded polystyrene (EPS), extruded polystyrene (XPS), and their composite formulations.
