Spiral stairways are prohibited except for special limited use and secondary access when a conventional stairway is not practical. Winding stairways may be installed on tanks and similar round structures where the diameter of the structure is a minimum of five feet.
Wash. Admin. Code § 296-307-26012
97-09-013, recodified as § 296-307-26012, filed 4/7/97, effective 4/7/97. Statutory Authority: RCW 49.17.040,[49.17.]050 and [49.17.]060. 96-22-048, § 296-306A-26012, filed 10/31/96, effective 12/1/96.