Ontario Building Code - Section 912

9.26.5.2. 2024 Building Code Compendium 202 Division B – Part 9 9.26.5.2. Materials (1) Eave protection shall be laid beneath the starter strip and shall consist of (a) No. 15 asphalt-saturated felt laid in two plies lapped 480 mm and cemented together with lap cement, (b) Type M or S roll roofing laid with not less than 100 mm head and end laps cemented together with lap cement, (c) glass fibre or polyester fibre coated base sheets, or (d) self-sealing composite membranes consisting of modified bituminous coated material. 9.26.6. Underlay Beneath Shingles 9.26.6.1. Materials (1) Except as required in Sentence (2), when underlay is used beneath shingles, it shall be (a) asphalt-saturated sheathing paper weighing not less than 0.195 kg/m², or (b) No. 15 plain or perforated asphalt-saturated felt. (See Note A-9.26.6.1.(1)) (2) Underlay used beneath wood shingles shall be breather type. 9.26.6.2. Installation (1) When used with shingles, underlay shall be installed parallel to the eaves with head and end lap of not less than 50 mm. (2) The top edge of each strip of underlay referred to in Sentence (1) shall be fastened with sufficient roofing nails to hold it in place until the shingles are applied. (3) The underlay referred to in Sentence (1) shall overlap the eave protection by not less than 100 mm. (See Article 9.26.10.2. for underlay beneath wood shakes.) 9.26.7. Asphalt Shingles on Slopes of 1 in 3 or Greater 9.26.7.1. Coverage (1) Coverage shall be not less than 2 thicknesses of shingle over the entire roof, disregarding cutouts. 9.26.7.2. Starter Strip (1) A starter strip shall be installed along the lower edge of the roof so that it extends approximately 12 mm beyond the eaves and rake of the roof and fastened along the bottom edge with nails spaced not more than 300 mm o.c. (2) Starter strips shall be (a) at least Type M mineral-surfaced roll roofing not less than 300 mm wide, (b) shingles of the same weight and quality as those used as a roof covering with tabs facing up the roof slope, or (c) pre-manufactured starter strips installed with sealant at the eaves. (3) Starter strips need not be provided where eave protection of not less than Type M mineral-surfaced roll roofing is provided or self-sealing composite membranes consisting of polyethylene and bituminous material is provided. 9.26.7.3. Head Lap (1) Shingles shall have a head lap of not less than 50 mm.