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296-24-74005  <<  296-24-74010 >>   296-24-74015

(Effective October 1, 2020)

PDFWAC 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
Figure D-8
[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060 and chapter 49.17 RCW. WSR 20-09-146, § 296-24-74010, filed 4/21/20, effective 10/1/20.]
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