Stairways and Vertical Openings

Section 370 Section 370.2750  Stairways and Vertical Openings a)         Interior stairways shall be enclosed with construction having one-third (⅓) hour fire resistance rating.  It shall exit directly to the outside grade, and have a door at all floors. b)         Light or ventilation shaft, chute and other vertical openings between stories shall be enclosed with construction having a fire resistance rating at least one-third (⅓) hour. c)         Every multi-level facility shall have stairways with a minimum headroom of six (6) feet, eight (8) inches and a maximum height of twelve (12) feet between landings; a minimum clear width of three (3) feet, except handrails which may project not more than three and one-half (3½) inches on each side, handrail is required only on one side of stair; width of treads exclusive of nosing or projection not less than nine (9) inches and risers of not more than eight (8) inches.  Stairways with triangular or winding treads or single risers are not acceptable. d)         Every stairway shall have a landing that is at least as deep as the width of the stairway door. e)         Usable space under stairs shall not be used for storage. f)         Means of egress such as stairs, stair landings, balconies, ramps and aisles, located along the edge of open-sided floors and mezzanines, shall have guardrails to prevent falls over the open side.