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.
