1924 ORDINANCES - Laserfiche WebLink

Home Browse Search

385 angles; such bars or angles shall be larger if the platform is wider or if the bradke is are farther apart. Each bracket shad be fastened at the top, to the wall, by a thro ugh bolt ( at least 7.8 inch diameter), nut, and washer ( at least 4 inch diameter.) the slope of the lower brackets bar shall be not lees than 30 degrees with the horizontal. The lower shall have a washer or shoulder to give sufficient bearing against the wall. The strength of the wall to which brackets are to be attached shall be carefully considered in determining the spacing, shape and inside connection of brack ets, so that under full load the wall will not be unduly strained. STAIRWAY3. Each stairway of an "A" fire escape shall be at least 24 inches 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. Each stairway of a "B" fire escape shall be at least 3 feet 4 inches wide between stringers; such stairway shell have a uniform rise of not more than 8 inches, and a uniform run of riot less than 9 inches. 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 dis. tance between the same points. Stairway stringers shall consist of either: (1) a 5 inch channel or larger. (2) two anles 2 x 2 x 1/4 inch or larger. (3) Two flat bars 2 x 3/8 inch or larger. (4) one flat bar 6 x 1/4 inch or larger. If two angles or two flat bars are used, they a«all be properly tied together by lattice bars, vertical as well as horizontal. If flat bare 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. Treads shall consist of either flat or square bars (not round) of the We and spacing specified for plat -forms. An "A" tread shall consist of at least six square bars, of seven flat bars. An "A" tread shall consist of at least six square bars, or seven flat bars. A "B" tread shall consist of at least seven square bare, or seven flat bars. A "®" thead shall consist of at least seven square bars, or eight flat bare,* A "B" tread made of flat bars shall have separators and bolt through the canter. A"B" tread made ofsquare bars shall be trussed. Treads and platforms may be solid if covered by a roof. BALANCED STAIRWAY. All "B" fire escapes, and all fire escapes on schools, theatres, and assembly halls, either shall reach to the ground or shall have a balanced stairway reaching to the ground. Every balanced stairway shall conform to the requirements for other stair- ways except that the stringers and the top rail may be lighter if they are properly trussed• The counterbalancing device Shall be attached to both sides of thestairway equally, or 8 special attachment shall be used to prevent warping or twisting. The counterbalancing devlc shall operate gradually and easily as the live load is applied. Cable counterweights are not permitted* Treads for "A" balanced stairways may be made s w • two 1-1/4% 1-1/4% y y a follows: inch angles ar front and back; two 1-1/4 x 1/4 inch bare between, lying flatwise; one inch space between bars. Treads for "B" balanced stairways may be made as follows: Two A