WAC 296-24-74010. Standard stairs

In addition to WAC 296-24-74005 , you must also ensure standard stairs: (1) Are installed at angles between 30 to 50 degrees from the horizontal. (2) Have a maximum riser height of 9.5 inches (24 cm). (3) Have a minimum tread depth of 9.5 inches (24 cm). (4) Have a minimum width of 22 inches (56 cm) between vertical barriers (see Figure D-8 of this section). EXCEPTION: Subsections (2) and (3) of this section do not apply to standard stairs installed prior to October 1, 2020, provided those stairs meet the dimension requirements specified in Table D-1 of this section or they use a combination that achieves the angle requirements of subsection (1) of this section. TABLE D-1 Angle to Horizontal Rise (in inches) Tread Run (in inches) 30°35' . . . . 6 1/2 11 32°08' . . . . 6 3/4 10 3/4 33°41' . . . . 7 10 1/2 35°16' . . . . 7 1/4 10 1/4 36°52' . . . . 7 1/2 10 38°29' . . . . 7 3/4 9 3/4 40°08' . . . . 8 9 1/2 41°44' . . . . 8 1/4 9 1/4 43°22' . . . . 8 1/2 9 45°00' . . . . 8 3/4 8 3/4 46°38' . . . . 9 8 1/2 48°16' . . . . 9 1/4 8 1/4 49°54' . . . . 9 1/2 8 Angle to Horizontal Rise (in inches) Tread Run (in inches) 30°35' . . . . 6 1/2 11 32°08' . . . . 6 3/4 10 3/4 33°41' . . . . 7 10 1/2 35°16' . . . . 7 1/4 10 1/4 36°52' . . . . 7 1/2 10 38°29' . . . . 7 3/4 9 3/4 40°08' . . . . 8 9 1/2 41°44' . . . . 8 1/4 9 1/4 43°22' . . . . 8 1/2 9 45°00' . . . . 8 3/4 8 3/4 46°38' . . . . 9 8 1/2 48°16' . . . . 9 1/4 8 1/4 49°54' . . . . 9 1/2 8 Figure D-8