Cedar Roof Shakes Size and Thickness

(1)  Shakes shall be not less than 450 mm long and not less than 100 mm nor more than 350 mm wide with a butt thickness of not more than 32 mm and not less than 9 mm.


Article Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.


Cedar hand-split shakes must not be less than 450 mm (18 in.) long and 100 mm (4 in.) wide, and no wider than 350 mm (133⁄4 in.). The butt thickness should be between 9 and 32 mm (3⁄8 and 11⁄4 in.) (Figure 103).

Shakes may be applied over spaced or closed roof sheathing. When spaced sheathing is
used (Figure 98), apply 19 × 89 mm (1 × 4 in. nominal) or wider strips on centre equal to the weather exposure at which the shakes are to be laid, but never more than 250 mm (10 in.). Closed roof sheathing is recommended for areas where wind-driven snow conditions prevail.

An exposure of 190 mm (71⁄2 in.) is recommended for 450 mm (18 in.) long shakes, and 250 mm (10 in.) for 600 mm (24 in.) long shakes. The minimum recommended roof pitch for hand-split shakes is 1:3. A 900 mm (36 in.) strip of No. 15 roofing felt should be laid over the sheathing boards at the eave line. The beginning or starter course of shakes should be doubled; for extra texture, it can be tripled. The bottom course or courses can be 380 mm (15 in.) or 450 mm (18 in.) shakes.

Figure 103

Installation of hand-split shakes

Source : Canada Mortgage and Housing Corporation (CMHC)

Note : Cedar shake shingles are an excellent option for home owners who want to save money on maintenance, while still enjoying the natural beauty and longevity of a cedar roof. Cedar shake shingles take the shape of large fish scales, making them easy to install and maintain. Cedar is a natural rot resistant, which means that it doesn’t need any additional treatment such as oiling or sealing. Cedar shake shingles do not have any chemicals added; they are safe for children and pets, so you don’t have to worry about anyone falling through the roof.