Section R. 400.18631 - Inside stairwaysRule 631.
(1) An inside stairway that forms an approved means of egress shall have suitable handrails on each side.(2) An inside stairway that forms an approved means of egress shall be not less than 44 inches wide in the clear. Handrails attached to walls shall not project into the required width of a stairway more than 3 1/2 inches at each side.(3) A stairway that forms an approved means of egress shall have treads that are not less than 9 1/2 inches wide, exclusive of the nosing, and risers that shall not be more than 7 3/4 inches in height. Treads and risers shall be of uniform width and height in each individual stairway.(4) An inside stairway which forms a means of egress which consists of 2 or more steps shall have stair treads of uniform width.(5) The maximum vertical distance between platforms or landings in any flight of stairs shall not be more than 9 feet.Mich. Admin. Code R. 400.18631