The Ontario Building Code | Attachment
9.27.5.1. Attachment
(1) Except as permitted in Sentences (2) to (7), cladding shall be fastened to the framing members or furring members, or to blocking between the framing members.
(2) Vertical lumber and stucco lath or reinforcing are permitted to be attached to sheathing only where the sheathing consists of not less than,
(a) 14.3 mm lumber,
(b) 12.5 mm plywood, or
(c) 12.5 mm OSB or waferboard.
(3) Vertically applied metal siding and wood shingles and shakes are permitted to be attached to the sheathing only where the sheathing consists of not less than,
(a) 14.3 mm lumber,
(b) 7.5 mm plywood, or
(c) 7.5 mm OSB or waferboard.
(4) Asbestos-cement shingles are permitted to be attached to the sheathing only when the sheathing consists of not less than,
(a) 14.3 mm lumber,
(b) 9.5 mm plywood, or
(c) 9.5 mm OSB or waferboard.
(5) Where wood shingles or shakes are applied to sheathing that is not suitable for attaching the shingles or shakes, the shingles or shakes may be attached to a wood lath not less than 38 mm by 9.5 mm thick securely nailed to the framing and applied as described in Article 9.27.7.5.
(6) Where asbestos-cement shingles are applied to sheathing that is not suitable for attaching the shingles, the shingles may be fastened to a wood lath not less than 89 mm by 9.5 mm thick securely nailed to the framing.
(7) Lath referred to in Sentence (6) shall be applied so that it overlaps the preceding shingle course by not less than 20 mm.