WAC 296-24-74020. Spiral stairs

In addition to WAC- 296-24-74005 , you must also ensure spiral stairs: (1) Have a minimum clear width of 26 inches (66 cm); (2) Have a maximum riser height of 9.5 inches (24 cm); (3) Have a minimum headroom above spiral stair treads of at least 6 feet 6 inches (2 m), measured from the leading edge of the tread; (4) Have a minimum tread depth of 7.5 inches (19 cm), measured at a point of 12 inches (30 cm) from the narrower edge; and (5) Have a uniform tread size.