The Ontario Building Code | Penetration of Fasteners
9.27.5.7. Penetration of Fasteners
(1) Fasteners for shakes and shingles shall penetrate through the nail-holding base or not less than 19 mm into the framing.
(2) Fasteners for cladding other than that described in Sentence (1) shall penetrate through the nail-holding base or not less than 25 mm into the framing.
9.27.6. Lumber Siding