"Nose or nosing" means the part of a tread projecting beyond the face of the riser immediately below.
"Open riser" means the air space between the treads of stairways without risers.
"Platform" means an extended step or landing breaking a continuous run of stairs.
"Railing" means a vertical barrier erected along exposed sides of stairways and platforms to prevent people from falling. The top part of the railing usually serves as a handrail.
"Rise" means the vertical distance from the top of a tread to the top of the next higher tread.
"Riser" means the upright part of a step at the back of a lower tread and near the leading edge of the next higher tread.
"Stairs or stairway" means a series of steps. A series of steps and landings having three or more risers constitutes stairs or a stairway.
"Tread" means the horizontal part of a step.
"Tread run" means the horizontal distance from the leading edge of a tread to the leading edge of an adjacent tread.
"Tread width" means the horizontal distance from front to back of tread, including nosing.
[WSR 97-09-013, recodified as § 296-307-26006, filed 4/7/97, effective 4/7/97. Statutory Authority: RCW
49.17.040, [49.17.]050 and [49.17.]060. WSR 96-22-048, § 296-306A-26006, filed 10/31/96, effective 12/1/96.]