9.27.3.3 — Required Sheathing Membrane and Installation

(1) Where non-wood-based rigid exterior insulating sheathing, or exterior insulating sheathing with an integral sheathing membrane is installed, a separate sheathing membrane is not required. (2) Where insulating sheathing is installed as provided in Sentence (1), (a) sheathing panels subject to moisture deterioration shall be sealed at all joints, and (b) the joints of sheathing panels not subject to moisture deterioration shall be, (i) sealed at all joints, or (ii) lapped or tongue and groove, and detailed to ensure drainage of water to the exterior.

(1) Except as provided in Article 9.27.3.6., where no sheathing is used, at least two layers of sheathing membrane shall be applied beneath the cladding. (2) All joints in the sheathing membrane required in Sentence (1) shall occur over framing, and the membrane shall be fastened to the framing with roofing nails or staples spaced not more than 150 mm along the edges of the outer layer of sheathing paper. (3) Wall sheathing is permitted to be used in lieu of one layer of sheathing membrane required in Sentence (1), and the thickness need not conform to Table 9.23.16.2.A.

(1) Sheathing membrane is permitted to be omitted beneath cladding when the joints in the cladding are formed to effectively prevent the passage of wind and rain in conformance with Sentence (2) or (3), as applicable. (2) Cladding consisting of sheets of plywood, hardboard, OSB, waferboard or fibre cement is considered to meet the requirements of Sentence (1), provided the cladding is applied so that, (a) all edges are directly supported by framing, (b) the vertical joints between adjacent sheets are sealed and, (i) covered with battens, (ii) shiplapped, or (iii) otherwise matched to provide weathertight joints, and (c) the horizontal joints between adjacent sheets are sealed and, (i) shiplapped, or (ii) otherwise matched to provide weathertight joints. (3) Metal siding consisting of sheets of metal is considered to meet the requirements of Sentence (1) where the joints between sheets are of the locked-seam type.