The Ontario Building Code | Fasteners
(1) Except as provided in Sentence (2), shingles shall be fastened with at least four nails or staples for 1 000 mm wide shingles so that no nails or staples are exposed.
(2) Where staples with an 11 mm crown are used, shingles shall be fastened with at least six staples.
(3) Fasteners may be reduced for narrower shingles in proportion to the width of the shingle or when shingles incorporating interlocking devices are used.
(4) Fasteners referred to in Sentences (1) and (2) shall be located 25 mm to 40 mm from each end of each strip shingle with other fasteners equally spaced between them.
(5) Fasteners referred to in Sentences (1) and (2) shall be located not less than 12 mm above the tops of the cutouts.