Section R. 408.41129 - Double-cleat ladders; width; additional rail; side railsRule 1129.
(1) The width between outside rails of a double-cleat ladder shall be not less than 38 inches or more than 46 inches .(2) A double-cleat ladder shall have an additional rail located at the center of the ladder(3) The side rails and middle rail for a double-cleat ladder shall be not less than nominal 2-inch by 4-inch construction grade lumber for double-cleat ladders less than 12 feet in length and not less than nominal 2-inch by 6-inch construction grade lumber for a double-cleat ladder from 12 feet to 24 feet in length .(4) The side rails of a double-cleat ladder shall be secured at the bottom and as close as possible to the top to prevent moving or toppling .Mich. Admin. Code R. 408.41129