For single- and two-family dwellings in California, guardrails (guards) are required at open-sided walking surfaces, including stairs, ramps, and landings, that are more than 30 inches above the floor or grade below. The main requirements are:
- Minimum height: Guards must be at least 36 inches (914 mm) in height, measured vertically above the adjacent walking surface or at the edge of a landing, balcony, porch, deck, or similar surface. On the open sides of stairs, the minimum height is 34 inches (864 mm) measured vertically from a line connecting the nosings.
- Where the top of a guard also serves as a handrail on stairs, the top must be between 34 inches (864 mm) and 38 inches (965 mm) above a line connecting the stair nosings.
- Openings in guards may not allow passage of a sphere 4 inches (102 mm) in diameter, except: Triangular openings formed by stair riser, tread, and bottom rail may allow a 6-inch sphere; openings on the side of stairs can allow a 4 3/8-inch sphere.
- Guards must be able to resist specific structural loads for safety.
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Confidence Score: 100
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Reference Clause Section Codes and File Names:
- R312.1.2, R312.1.3, R312.2, R321.1.3, R301, R301.5 — 2025 CRC Residential Code
- 1015.3, 1015.4 — 2025 CBC Building Code
- Original Referenced Articles:
"R312.1.2 Height. Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 36 inches (914 mm) in height measured vertically above the adjacent walking surface. Exceptions: 1. Guards on the open sides of stairs shall have a height not less than 34 inches (864 mm) measured vertically from a line connecting the nosings. 2. Where the top of the guard also serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) as measured vertically from a line connecting the nosings."
"R321.1.3 Opening limitations. Required guards shall not have openings from the walking surface to the required guard height that allow passage of a sphere 4 inches (102 mm) in diameter. Exceptions: 1. The triangular openings at the open side of stair, formed by the riser, tread and bottom rail of a guard, shall not allow passage of a sphere 6 inches (153 mm) in diameter. 2. Guards on the open side of stairs shall not have openings that allow passage of a sphere 4 3/8 inches (111 mm) in diameter." — 2025 CRC Residential Code
"1015.3 Height. Required guards shall be not less than 42 inches (1067 mm) high, measured vertically as follows: ... Exceptions: For occupancies in Group R-3, and within individual dwelling units in occupancies in Group R-2, guards on the open sides of stairs shall have a height not less than 34 inches (864 mm) measured vertically from a line connecting the nosings. For occupancies in Group R-3, and within individual dwelling units in occupancies in Group R-2, where the top of the guard serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) measured vertically from a line connecting the nosings." — 2025 CBC Building Code
"1015.4 Opening limitations. Required guards shall not have openings that allow passage of a sphere 4 inches (102 mm) in diameter from the walking surface to the required guard height. Exceptions: 2. The triangular openings at the open sides of a stair, formed by the riser, tread and bottom rail shall not allow passage of a sphere 6 inches (152 mm) in diameter." — 2025 CBC Building Code
- Groundedness Check: The answer directly uses the requirements and language as found in the 2025 CRC Residential Code and 2025 CBC Building Code, specifically in sections for guard height, opening limitations, and exceptions pertinent to single- and two-family dwellings. Therefore, the answer is factually correct and grounded in the referenced local codes.