Wood shingles must be installed on slopes that are at least 3:12 or greater. They must be made of a naturally durable wood of grades 1, 2, or 3 approved by the Cedar Shake and Shingle Bureau. A label of an approved grading or inspection bureau or agency must identify each bundle of shingles.
Wood shingles must be installed in accordance with the manufacturers instructions and the following.
Wood shingles must be laid with a side lap of not less than 1 ½ inch between joints in courses and no two joints in any three adjacent courses shall be in direct alignment. Spacing between shingles may not be less than ¼ inch nor more than 3/8 inch. Weather exposure may not exceed what is specified in the accompanying table.
Wood shingles must be attached to the roof with two fasteners per shingle. Fasteners should be not more than ¾ inch from the edge of the shingle and not more than 1 inch above the exposure line.
Wood Shingle Weather Exposure (Inches) and Roof Slope