O-1954-476 - Laserfiche WebLink

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.,------' " -, , .., -.::::!!' ,,'" " e . - 20- '!READS AND RISmS. (a) Treads and risers or required stairs shall be so proportioned that the product of the width of tread, exclusive of nosing, and the height of riser, in inches, shall be not less than 70 nor more than 75; but risers shall not exceed 7 3/4 inches in height, and treads, exclusive or nosing, shall be not less than 9-! inches wide; ex cept that in schools the proportion and dimensions of the treads and riseJ:"s may, in t he discretion of the building official, be adjusted to suit the age of the pupils for -which the school is intended. Treads and risers shall be of uniform width and height in anyone story. (b) The use of winders is prohibited in required stairwB\Y's. 9. LANDllias. (a) No flight of stairs shall have a vertical rise of more t han 12 feet between floors or landings; except that in stairways s~rving as exits in public buildings such vertical rise shall not exceed 8 feet. (b), The length and width of landings shall not be less than the width of stairways in which they occur. 10. HANDRAIIS . (a) Except for steps in aisles, stairs shall have walls or well secU1'ed balustrades or guards on both sides. ' (b) Such stairs when less than 44 inches in w.i.dth shall have hand.- rails on at least one side. (c) SUch stairs when required to be 44 :inches or more in width shall have handrails on both sides. (d) When the required width of a flight or stairs exceeds 88 inches, an intermediate handrail, cont:inuous between landings, secU1'ely supported and termin:inating at ih e upper end in newels or standards at least 6 feet high, with no projections, shall be prov;i.ded. 11. EnT HALnVAYS. 'L'heclear width of every hallway or passage leading to a required exl..t shan be 'not less than at the rate of 12 inches for every 100 persons to b e accommodated by the hallway but not less than 44 inches; proVided that in nmltifamily houses or in case less than 40 persons are to be accomodated, the mi.ni.mu.m clear widith may be 36 inches. 12. WIDTH OF mORWAYB. ~e aggt'egate clear width of doorw'ays serving as requ:ired exl..ts shall be .not less than at the rate of 22 inches for every 100 persons to be acconunodated. No exit doorway serving as an exit for more than 40 persons shall have a clear width of less than 34 inches (nominal 36-inch door.)