1123A Interior Stairways — 2025 California Building Code

Interior stairways serving buildings containing covered multifamily dwelling units shall comply with this section.

Open risers shall not be permitted on interior stairways.

Exception: Stairways within an individual dwelling unit.

All tread surfaces shall be stable, firm and slip resistant, and shall comply with Section 1119A.2. Treads shall have smooth, rounded or chamfered exposed edges and no abrupt edges at the nosing (lower front edge).

Nosing shall not project more than 1 1/4 inches (31.8 mm) past the face of the riser below. Risers shall be sloped or the underside of the nosing shall have an angle not more than 30 degrees (0.52 rad) from the vertical. (See Figure 11A-6A.)

Interior stairs shall have the upper approach and lower tread marked by a stripe providing clear visual contrast.

The stripe shall be a minimum of 2 inches (50.8 mm) wide to a maximum of 4 inches (101.6 mm) wide placed parallel to, and not more than 1 inch (25.4 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.

Exception: Striping is not required for stairways within individual dwelling units.

1123A.6.1 Where required. Stairways shall have handrails on each side. Intermediate handrails shall be located equidistant from the sides of the stairway and comply with Section 1014.9.

Exception: Stairways serving an individual dwelling unit may have one handrail, except that stairways open on one or both sides shall have handrails on the open side or sides.

1123A.6.2 Handrail configuration.

1123A.6.2.1 Handrail heights. The top of handrails shall be 34 to 38 inches (864 to 965 mm) above the nosing of the treads.

1123A.6.2.2 Handrail continuity. Handrails on all stairways shall be continuous within the full length of each stair flight. Inside handrails on switchback or dogleg stairs shall be continuous between stair flights.

1123A.6.2.3 Handrail extensions. At the top of stair flights, handrails shall extend a minimum of 12 inches (305 mm) horizontally above landings, beginning directly above the first riser nosing. Extensions shall return to a wall, guard or the walking surface, or shall be continuous to the handrail of an adjacent stair flight.

At the bottom of stair flights, handrails shall extend at the slope of the stair flight for a distance equal to one tread depth beyond the last riser nosing. Such extension shall continue with 12 inches (305 mm) minimum horizontal extension, shall be contin- uous to the handrail of an adjacent stair flight, or shall return to a wall, guard or the walking surface. Handrail horizontal extensions shall be in the same direction as the stair flights. (See Figures 11A-6A and 11A-6E.)

Exception: Stairways within an individual dwelling unit.

1123A.6.2.4 Handrail projections. Handrails projecting from a wall shall have a space of 1 1/2 inches (38.1 mm) minimum between the wall and the handrail.

Handrails may be located in a recess if the recess is a maximum of 3 inches (76.2 mm) deep and extends at least 18 inches (457 mm) above the top of the rail. Any wall or other surface adjacent to the handrail shall be free of sharp or abrasive elements. (See Figure 11A-6B.)

1123A.6.2.5 Handrail gripping surfaces. Handrail gripping surfaces shall be continuous along their length, and shall not be obstructed along their tops or sides. The bottoms of handrail gripping surfaces shall not be obstructed for more than 20 percent of their length. When provided, horizontal projections shall occur 1 1/2 inches (38 mm) minimum below the bottom of the hand- rail gripping surface. The distance between horizontal projections and the bottom of the gripping surface shall be permitted to be reduced by 1/8 inch (3.2 mm) for each 1/2 inch (12.7 mm) of additional handrail perimeter dimension that exceeds 4 inches (102 mm).

Handrail gripping surfaces and any surfaces adjacent to them shall be free of sharp or abrasive elements, and shall have rounded edges.

1123A.6.2.6 Cross section. Handrail gripping surfaces shall comply with this section, or the shape shall provide equivalent grip- ping surface.

1. Circular cross section. The handrail gripping surfaces with a circular cross section shall not be less than 1 1/4 inches (31.75 mm) nor more than 2 inches (50.8 mm) in cross-sectional dimension.

2. Noncircular cross section. Handrail gripping surfaces with a noncircular cross section shall have a perimeter dimension of 4 inches (102 mm) minimum and 6 1/4 inches (159 mm) maximum, and a cross-section dimension of 2 1/4 inches (57 mm) maximum.

1123A.6.2.7 Fittings. Handrails shall not rotate within their fittings.

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