11B-504 Stairways — 2025 California Building Code
California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-09-25 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Building Code (Title 24, Part 2) § 11B-504 · Effective January 1, 2026 · Official source: Building Standards Commission
11B- 504.1 General. Stairs shall comply with Section 11B- 504 .
11B- 504.2 Treads and risers. All steps on a flight of stairs shall have uniform riser heights and uniform tread depths. Risers shall be 4 inches ( 102 mm) high minimum and 7 inches ( 178 mm) high maximum. Treads shall be 11 inches ( 279 mm) deep minimum.
Exception: Curved stairways with winder treads are permitted at stairs which are not part of a required means of egress.
11B- 504.3 Open risers. Open risers are not permitted.
Exceptions: 1. On exterior stairways, an opening of not more than 1/2 inch (12.7 mm) may be permitted between the base of the riser and the tread.
2. On exterior stairways, risers constructed of grating containing openings of not more than 1/2 inch (12.7 mm) may be permitted.
11B- 504.4 Tread surface. Stair treads shall comply with Section 11B- 302. Changes in level, slopes exceeding 1:48, and detectable warnings shall not be permitted.
Exception: Reserved.
11B-504.4.1 Contrasting stripe. Interior stairs shall have the upper approach and lower tread marked by a stripe providing clear visual contrast. Exterior stairs shall have the upper approach and all treads marked by a stripe providing clear visual contrast.
The stripe shall be a minimum of 2 inches (51 mm) wide to a maximum of 4 inches (102 mm) wide placed parallel to, and not more than 1 inch (25 mm) from, the nose of the step or upper approach. The stripe shall extend the full width of the step or upper approach and shall be of material that is at least as slip resistant as the other treads of the stair. A painted stripe shall be acceptable. Grooves shall not be used to satisfy this requirement.
11B- 504.5 Nosings. The radius of curvature at the leading edge of the tread shall be 1/2 inch ( 12.7 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 1/4 inches (32 mm) maximum over the tread below.
Exception: In existing buildings there is no requirement to retroactively alter existing nosing projections of 1 1/2 inches (38 mm) which were constructed in compliance with the building code in effect at the time of original construction.
FIGURE 11B -504.5—STAIR NOSINGS
ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMMODATIONS, COMMERCIAL BUILDINGS AND PUBLIC HOUSING
11B- 504.6 Handrails. Stairs shall have handrails complying with Section 11B- 505 .
11B- 504.7 Wet conditions. Stair treads and landings subject to wet conditions shall be designed to prevent the accumulation of water.
11B-504.8 Floor identification. Floor identification signs required by Chapter 10, Section 1023.9 complying with Sections 11B-703.1, 11B-703.2, 11B-703.3 and 11B-703.5 shall be located at the landing of each floor level, placed adjacent to the door on the latch side, in all enclosed stairways in buildings two or more stories in height to identify the floor level. At the exit discharge level, the sign shall include a raised five pointed star located to the left of the identifying floor level. The outside diameter of the star shall be the same as the height of the raised characters.
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