Securing of Tabs Asphalt Shingles on Slopes of 1 in 3 or Greater
(1) Shingle tabs shall be secured by a spot of plastic cement not exceeding 25 mm diam under the centre of each tab or by interlocking devices or self-sealing strips.
Article 126.96.36.199 Ontario Regulation 332/12 Building Code, Information published by oncodes.ca for educational purposes only.
Exposed portion of the shingle
To avoid defacing the exposed surface of the shingles with cement, the band should be located between 25 and 50 mm (1 and 2 in.) above the butt edge of each succeeding course of shingles. Staple or nail each shingle strip in place with four fasteners located above the exposed portion of the shingle. If cold-application cement is used, it should be applied at a rate of approximately 0.5 L/m2 (1 gal./100 sq. ft.) of cemented area. Hot-application cement is applied at a rate of approximately 1 kg/m2 (0.2 lb./sq. ft.) of cemented area. This technique is necessary only for slopes lower than 1:4 since there are special low slope shingles of sufficient length to maintain the three thicknesses necessary at roof pitches of 1:4 or greater.
Source : Canada Mortgage and Housing Corporation (CMHC)