PROWAG (36 CFR 1190)Public Domain

R408 — Stairs

Chapter 4: Supplemental Technical Requirements

R408.1 General. Stairs shall comply with R408. R408.2 Treads and Risers. All steps on a flight of stairs shall have uniform riser heights and uniform tread depths. Risers shall be 4 inches (100 mm) high minimum and 7 inches (180 mm) high maximum. Treads shall be 11 inches (280 mm) deep minimum. R408.3 Open Risers. Open risers are not permitted. R408.4 Tread Surface. Stair treads shall comply with R302.6, except that changes in level are not permitted. Exception: Treads shall be permitted to have a slope not steeper than 1:48 (2.1%). R408.5 Nosings. The radius of curvature at the leading edge of the tread shall be 1/2 inch (13 mm) maximum. Nosings that project beyond risers shall have the underside of the leading edge curved or beveled. Risers shall be permitted to slope under the tread at an angle of 30 degrees maximum from vertical. The permitted projection of the nosing shall extend 1 1/2 inches (38 mm) maximum over the tread below. R408.6 Visual Contrast. The leading edge of each step tread and top landing shall be marked by a stripe. The stripe shall be 1 inch (25 mm) wide minimum and shall contrast visually with the rest of the step tread or circulation path surface either light-on-dark or dark-on-light. R408.7 Handrails. Stairs shall have handrails complying with R409.

← PreviousR407 Next →R409

Public Domain: PROWAG (36 CFR Part 1190, U.S. Access Board) is a U.S. government publication and is not subject to copyright. Text extracted from the official source ↗. Figures are served from the eCFR; if one does not load, use the link in its place.