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ICC A117.1-2009 Cl-5.General Site and Building Elements <br /> 11 min 504.6 Handrails. Stairs shall have handrails complying <br /> 280 with Section 505. <br /> 504.7 Wet Conditions. Stair treads and landings sub- <br /> ject to wet conditions shall be designed to prevent the <br /> accumulation of water. <br /> 504.8 Lighting. Lighting for interior stairways shall <br /> 4-7 comply with Section 504.8. <br /> 100-180 504.8.1 Illumination Level. Lighting facilities shall <br /> be capable of providing 10 foot-candles (108 lux) of <br /> illuminance measured at the center of tread surfaces <br /> and on landing surfaces within 24 inches (610 mm) <br /> of step nosings. <br /> 504.8.2 Lighting Controls. If provided, occupancy- <br /> FIG.504.2 sensing automatic controls shall activate the stairway <br /> TREADS AND RISERS FOR ACCESSIBLE STAIRWAYS lighting so the illuminance level required by Section <br /> 504.8.1 is provided on the entrance landing, each <br /> 504.4 Tread Surface. Stair treads shall comply with stair flight adjacent to the entrance landing, and on <br /> Section 302 and shall have a slope not steeper than the landings above and below the entrance landing <br /> 1:48. prior to any step being used. <br /> Nosings. The radius of curvature at the leading 504.9 Stair Level Identification. Stair level identifica- <br /> 504.5 <br /> edge of the tread shall be '/2 inch (13 mm) maximum. tion signs in raised characters and braille complying <br /> Nosings that project beyond risers shall have the under- ' <br /> with Sections 703.3 and 703.4 shall be located at each <br /> sidefloor level landing in all enclosed stairways adjacent to <br /> of the leading edge curved or beveled. Risers shall <br /> bethe door leading from the stairwell into the corridor to <br /> permitted to slope under the tread at an angle of 30 <br /> degrees maximum from vertical. The permitted projec- identify the floor level. The exit door discharging to the <br /> outside or to the level of exit discharge shall have a sign I <br /> tion of the nosing shall be 1V2 inches (38 mm) maxi- with raised characters and braille stating"EXIT." <br /> mum over the tread or floor below. <br /> 504.5.1 Visual contrast. The leading 2 inches (51 505 Handrails <br /> mm) of the tread shall have visual contrast of dark- 505.1 General. Handrails required by Section 405.8 for <br /> on-light or light-on-dark from the remainder of the ramps, or Section 504.6 for stairs, shall comply with <br /> tread. Section 505. <br /> 11/2 max <br /> 38 <br /> radius 1/2 max typical <br /> 13 <br /> curved <br /> (a)Vertical Riser (b)Curved Nosing <br /> 11/2 max <br /> 38 <br /> 30°max <br /> beveled <br /> (c)Beveled Nosing (d)Angled Riser <br /> FIG.504.5 62-0{ „_1` <br /> STAIR NOSINGS <br />