PDFWAC 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.
[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060 and chapter 49.17 RCW. WSR 20-09-146, amended and recodified as § 296-24-74020, filed 4/21/20, effective 10/1/20. Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, and 49.17.060. WSR 15-24-100, § 296-24-76515, filed 12/1/15, effective 1/5/16; Order 73-5, § 296-24-76515, filed 5/9/73 and Order 73-4, § 296-24-76515, filed 5/7/73.]