§ 50.25. Stair towers.
(a) A stair tower shall be a stairway which is separated from all floors or areas of the building. Stair towers shall lead directly to grade by an exit discharge.
(b) Stair towers shall be Class A or Class B types in accordance with the following table:
Class A Stair Class B Stair Minimum clear width in inches 40" 36" Maximum height of riser 7 1/2" 8" Minimum width of tread 10" 9" Maximum angle of stairs in degrees 33° 40° Required handrails (Each handrail is allowed to project 3" without decreasing minimumclear width) Both sides One side under 40" in width, both sides 40" or more in width Maximum vertical distances between landings 9' 12' (c) The minimum width of landings shall be the same width as the stairs they serve. Intermediate landings on straight run stairs shall have a minimum length of 3 feet.
(d) The narrowest width in a stairway or landing serving a stairway shall determine the units of width for the entire stairway.
(e) There shall be no variation in the width of treads or the height of risers in any flight. Variation in height of risers in adjacent flights shall not exceed 1/4 inch. All treads less than 10 inches, as measured horizontally between the face of risers, shall have an effective projection of approximately 1 inch beyond the face of the riser below.
(f) Where material of stair treads and landings is such as to present a danger of slipping, nonskid material shall be applied.
(g) No arrangement of treads known as winders shall be permitted in required exit stairways.
(h) Stairways, landings, balconies, open sided floors, and the like shall have well-secured handrails. The clear distance between handrail and wall or other obstruction shall be not less than 1 1/2 inches. Longitudinal rails or balusters or both shall be provided. Balusters shall be spaced not more than 6 inches apart. Longitudinal rails shall not exceed 6 inches measured at right angles to the rails. The lowest rail shall be measured vertically from the tread nosing.
(i) Handrails on stairs shall be not less than 30 inches nor more than 34 inches above the upper surface of the tread, measured vertically to the top of the rail, from a point on the tread 1 inch back from the leading edge.
(j) Handrails shall be provided on any stair landing, balcony, ramp, aisle, and the like located along the edge of open sided floors or mezzanines to prevent falls over the open side. Railings protecting open sides of landings, balconies, mezzanines, and the like shall be at least 42 inches high.
(k) Storage or obstructions of any kind shall not be permitted in stair towers.
(l) A door opening into a stair tower shall at no point in its swing reduce the required units of width of the stair or landing.
(m) Every door to a stairway shall open onto a landing at least as wide as the stairs.
(n) Doors and frames used in connection with stair towers shall be of approved label and be of substantial construction, installed in a workmanlike manner, fitted with reliable hardware of approved label and shall be of the side hinged, swing type.
(o) Stair tower doors shall swing with the exit travel.
(p) Stair tower doors shall be provided with fire exit hardware. Exterior doors from stair towers may have panic hardware instead of fire exit hardware. No lock or other device which prevents egress shall be permitted on the doors during any period of occupancy.
(q) Stair tower doors shall be a minimum of 32 inches in width. Doors used in connection with stair towers shall be a minimum of 6 feet, 8 inches in height.
(r) Outside stairs shall be considered an exit when they meet the following conditions:
(1) Outside stairs shall meet the conditions listed in subsections (b)—(d), (f)—(j) and (l)—(q).
(2) Outside stairs shall only serve as an exit for floors three or fewer stories above grade.
(3) Outside stairs shall be accessible and unobstructed at all times of occupancy.
(4) Outside stairs shall be of substantial construction and installed in a workmanlike manner. Combustible construction may be used when floor panels are permitted to be combustible construction in the construction tables. Wood stringers shall be a minimum size of 2 inches by 10 inches stock material when treads are butt nailed or a minimum of 2 inches by 12 inches stock material when the stringers are sawed to accommodate the treads.
(5) Handrails shall be provided on both sides of outside stairs except that a handrail is not required along a solid wall when the dimensions from the exterior handrail to the solid wall is 36 inches or less.
(6) The building exterior wall shall be fire rated in accordance with the rating required for exterior walls in § 50.11 (relating to construction tables).
(7) All doors opening onto the outside stair and door assemblies located within 10 feet of any portion of the outside stair shall have a fire rating the same as the rating required for the exterior wall except that a door located at the top of the outside stair need not be fire rated. All other openings within 10 feet of either side or below the outside stair shall be glazed with 1/4 inch wire glass in steel frames.
Cross References This section cited in 34 Pa. Code § 50.23 (relating to means of egress capacity); 34 Pa. Code § 51.25 (relating to stair towers); 34 Pa. Code § 52.25 (relating to stair towers); 34 Pa. Code § 53.25 (relating to stair towers); 34 Pa. Code § 54.25 (relating to stair towers); 34 Pa. Code § 55.25 (relating to stair towers); 34 Pa. Code § 56.25 (relating to stair towers); 34 Pa. Code § 57.25 (relating to stair towers); 34 Pa. Code § 58.25 (relating to stair towers); and 34 Pa. Code § 59.25 (relating to stair towers).
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