IBC Chapter Ten - Means of Egress
1009.3.2 Profile
Code Excerpt:
1009.3.2 Profile.
The radius of curvature at the leading edge of the tread shall be not greater than .5 inch (12.7 mm). Beveling of nosings shall not exceed .5 inch (12.7 mm). Risers shall be solid and vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 degrees (.52 rad) from the vertical. The leading edge (nosings) of treads shall project not more than 1.25 inches (32 mm) beyond the tread below and all projections of the leading edges shall be of uniform size, including the leading edge s shall be of uniform size, including leading edge of the floor at the top of a flight.
Exceptions:
1. Solid risers are not required for stairways that are not required to comply with Section 1007.3, provided that the opening between treads does not permit the passage of a sphere with a diameter of 4 inches (102 mm).
2. Solid risers are not required for occupancies in Group I-3.
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