Mich. Admin. Code R. 408.30519 - Treads and risers
Rule 519. Sections R311.7.4.1 and R 311.7.4.2 of the
R311.7.4.1. Riser height. The maximum riser
height shall be 8 1/4 inches (210 mm). The riser shall be measured vertically
between leading edges of the adjacent treads. The greatest riser height within
any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5
mm)
R311.7.4.2. Tread depth. The
minimum tread depth shall be 9 inches (229 mm). The tread depth shall be
measured horizontally between the vertical planes of the foremost projection of
adjacent treads and at a right angle to the tread's leading edge. The greatest
tread depth within any flight of stairs shall not exceed the smallest by more
than 3/8 inch (9.5 mm). Winder treads shall have a minimum tread depth of 10
inches (254 mm) measured as above at a point 12 inches (305 mm) from the side
where the treads are narrower. Winder treads shall have a minimum tread depth
of 6 inches (152 mm) at any point. Within any flight of stairs, the greatest
winder tread depth at the 12-inch (305 mm) walk line shall not exceed the
smallest by more than 3/8 inch (9.5 mm).
Notes
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