WAC 296-56-60217. Spiral stairways

(1) Employers must meet the following requirements for spiral stairways: (a) Stairways must conform to the minimum dimensions of Figure F-1; Figure F-1 Spiral Stairway—Minimum Dimensions A (Half-tread width) B Normal use by employees . . . . 11 inches (27.9 cm) 6 inches (15.2 cm) Limited access . . . . 9 inches (22.9 cm) 5 inches (12.7 cm) Spiral Stairway—Minimum Dimensions A (Half-tread width) B Normal use by employees . . . . 11 inches (27.9 cm) 6 inches (15.2 cm) Limited access . . . . 9 inches (22.9 cm) 5 inches (12.7 cm) (b) Stairway risers must be uniform and range from six and one-half to 10.5 inches (16.5 to 26.67 cm) in height; (c) Minimum loading capability be 100 pounds per square foot (445 N), and minimum tread center concentrated loading shall be 300 pounds (1334 N); (d) Railing must conform to the requirements of WAC 296-56-60123 (3). If balusters are used, there must be a minimum of one per tread. Handrails must be a minimum of one and one-fourth inches (3.18 cm) in outside diameter; and (e) Vertical clearance must be at least six feet, six inches (1.98 m) above the top step. (2) Employers must maintain spiral stairways in safe condition.