Standard Stairs
The employer must ensure standard stairs installed after January 17, 2017: (See 1910.25 Figure D-8)
- are installed at angles between 30 to 50 degrees from the horizontal;
- have a minimum tread width of 22 inches (56 cm) between vertical barriers;
- have a minimum tread depth of 9.5 inches (24 cm); and
- have a maximum riser height of 9.5 inches (24 cm).
Spiral Stairs
The employer must ensure spiral stairs:
Spiral Stairs
- have a minimum clear width of 26 inches (66 cm);
- have a maximum riser height of 9.5 inches (24 cm);
- have a minimum headroom above spiral stair treads of at least 6 feet, 6 inches (2 m), measured from the leading edge of the tread;
- have a minimum tread depth of 7.5 inches (19 cm), measured at a point 12 inches (30 cm) from the narrower edge; and
- have a uniform tread size.
Alternating Tread-Type Stairs
The employer must ensure alternating tread-type stairs:
- have a series of treads installed at a slope of 50 to 70 degrees from the horizontal;
- have a distance between handrails of 17 to 24 inches (51 to 61 cm);
- have a minimum tread depth of 8.5 inches (22 cm); and have open risers if the tread depth is less than 9.5 inches (24 cm); and
- have a minimum tread width of 7 inches (18 cm), measured at the leading edge of the tread (i.e., nosing).
Knowledge Check Choose the best answer for the question.
1-7. Employers must ensure standard stairs are installed at angles _____.
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