(1)
Except as provided in Sentence (2), shingles shall be fastened with at least 4 nails or staples for 1 m 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 6 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.