Plywood panels as exterior cladding

Plywood sheets acceptable for use as a cladding material are made with a plain or grooved surface and are usually applied vertically. The joints may be V-grooved or flush or may be covered with battens. Some products have a resin-impregnated paper laminated to the face that provides a smooth, moisture-resistant surface that resists checking or splitting after painting or staining.

If a rainscreen is not required, plywood cladding may be applied directly over the sheathing membrane on unsheathed wall framing. The minimum thickness used is 6 mm (1⁄4 in.) for stud spacing of 400 mm (16 in.) on centre and 8 mm (5⁄16 in.) for spacing of supports up to 600 mm (24 in.) on centre when the face grain is installed at right angles to supports. Where the face grain is installed parallel to supports, the minimum thickness is 8 mm (5⁄16 in.) and 11 mm (7⁄16 in.) for studs spaced at 400 mm (16 in.) and 600 mm (24 in.), respectively.

Cut edges should be protected with a suitable paint or sealer before installation. A 2 to 3 mm (1⁄8 in.) space between the sides and ends of the panels and butted ends of the battens will permit expansion without bulging. Fill vertical joints with caulking or cover them with battens. Flash horizontal joints or lap them at least 25 mm (1 in.).

The edges of plywood panels should be supported and fastened with corrosion-resistant nails, usually 51 mm (2 in.) long. Space the nails not more than 150 mm (6 in.) along the edges and 300 mm (12 in.) at intermediate supports.

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