You must meet these requirements for new installations:

(1) Fixed stairs installed after October 3, 1983, must be positioned within the range of thirty degrees to fifty degrees to the horizontal with uniform riser height and tread width throughout each run and be capable of a minimum loading of one hundred pounds per square foot (445 N) and a minimum concentrated load of three hundred pounds (1334 N) at the center of any treadspan. Riser height must be from six to seven and one-half inches (15.24 to 19.05 cm), stair width a minimum of twenty-two inches (55.88 cm) between vertical barriers, and tread depth a minimum of 12 ± 2 inches (30.48 ± 5.08 cm), and tread nosing be straight leading edges.

(2) Stair landings must be at least twenty inches (50.8 cm) in depth. Where doors or gates open on a stairway, a landing platform must be provided. Door swing must not reduce the effective standing area on the landing to less than eighteen inches (45.72 cm) in depth.

(3) Fixed stairs having four or more risers must have stair railings or handrails complying with WAC 296-56-60123(3).

(4) The railing height from tread surface at the riser face must be 33 plus or minus 3 inches (83.82 cm plus or minus 7.62 cm).

(5) For restricted areas, when physical features require stairs steeper than those provided for by (1) of this subsection, stairs at angles of fifty degrees to seventy-five degrees from the horizontal may be used if they:

(a) Are capable of supporting a single concentrated load of two hundred pounds (890 N) at the tread centers;

(b) Have open treads at least four inches (10.16 cm) in depth and eighteen inches (45.72 cm) in width with a uniformly spaced vertical rise between treads of six to nine and one-half inches (15.24 to 24.13 cm); and

(c) Have handrails that meet the requirements of WAC 296-56-60123(3) on both sides that are not less than thirty inches (76.2 cm) in height from the tread surface at the riser face.

(6) You must maintain fixed stairways in safe condition and must not be obstructed.