(1) You 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) |
(b) Stairway risers must be uniform and shall range from six and one-half to ten and one-half inches (16.5 to 26.67 cm) in height;
(c) Minimum loading capability be one hundred pounds per square foot (445 N), and minimum tread center concentrated loading shall be three hundred 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) You must maintain spiral stairways in safe condition.