Section R. 408.41253 - Roofing brackets and crawling boardsRule 1253.
(1) A roofing bracket shall be installed in a manner to maintain a level working surface.(2) In addition to the pointed metal projections, the brackets shall be secured in place by nailing. When it is impractical to nail brackets, rope supports shall be used. When rope supports are used, they shall consist of first-quality manila rope of at least 3/4-inch diameter or its equivalent.(3) A crawling board shall not be less than 1 by 10 inches, shall extend from the eave to the ridge of the roof, and shall be secured against displacement.Mich. Admin. Code R. 408.41253