Section 375.18. Stairways.

 

(1)  Each stairway of an "A" type fire escape shall be at least 24 inches wide between stringers; such stairway shall have a uniform rise of not more than 8 inches, and a uniform run of not less than 8 inches.

(2)  Each stairway of a "B" type fire escape shall be at least 3 feet 4 inches wide between stringers; such stairway shall have a uniform rise of not more than 8 inches, and a uniform run of not less than 9 inches.

(3)  Stairway stringers shall consist of either:

(a) A 5 inch channel or larger.

(b) Two angles 2 × 2 × 1 / 4 inch or larger

(c) Two flat bars 2 × 3/ 8 inch or larger.

(d) One flat bar 6 × 1 / 4 inch or larger.

(4)  If 2 angles or 2 flat bars are used, they shall be properly tied together by lattice bars, vertical as well as horizontal. If flat bars are used, every stairway of more than 10 risers shall have lateral bracing. The connection of stringers to platform, at top and bottom, shall be at least equal in strength to the stringers and shall safely carry the full live and dead loads. If stringers are carried by intermediate brackets, the stringers shall have a horizontal bearing on the brackets and shall be properly and securely connected thereto.

(5)  Treads shall consist of either flat or square bars, (not round), of the size and spacing specified for platforms. An "A" tread shall consist of at least 6 square bars or 7 flat bars. A "B" tread shall consist of at least 7 square bars or 8 flat bars. A "B" tread made of flat bars shall have separators and bolt through the center. A "B" tread made of square bars shall be trussed. Treads and platforms may be solid if covered by a roof.

1-2-56 ; renum., Register, September, 1974, No. 225 , eff. 10-1-74.

Note

The rise is the vertical distance from the extreme edge of any step to the corresponding extreme edge of the next step. The run is the horizontal distance between the same points. Microsoft Windows NT 6.1.7601 Service Pack 1