The numbers, with the section they come from
Every figure below is quoted with its code section so you can check it yourself. Edition: 2025 California Residential Code, which applies to permits applied for on or after January 1, 2026.
- Stair riser height 7 3/4 inches maximumCRC R318.7.5.1
- The vertical face of each step. The tallest and shortest riser in a flight may differ by no more than 3/8 inch. Uneven steps are the most common reason a stair fails inspection.
- Stair tread depth 10 inches minimumCRC R318.7.5.2
- The part you stand on, measured nosing to nosing. Deeper is allowed and usually walks better on a deck.
- Stair width 36 inches minimumCRC R318.7.1
- Clear width above the handrail. Handrails may project into that width by a limited amount; the stair itself is not built narrower.
- Handrail height 34 to 38 inchesCRC R320.2
- Measured vertically from the nosing of each tread. A handrail is required on at least one side of any flight with four or more risers (CRC R318.7.8).
- Handrail grip Round: 1.25 to 2 inches acrossCRC R320.6
- A Type I handrail has to be graspable: a 4x4 post cap or a wide flat board is not a handrail, however solid it feels.
- Guard (deck railing) height 42 inches minimumCRC R321.1.2
- On the deck itself. This is where California differs from what many out-of-state guides say: 36 inches is not enough here.
- When a guard is required drop over 30 inchesCRC R321.1.1
- Measured to the grade or floor below, within 36 inches horizontally of the open edge. A low deck may need no guard at all; an inch over the line and it does.
- Guard on the stair side 34 inches minimumCRC R321.1.2 exception
- Measured from the line of the nosings. Where the top of that guard is also the handrail, it must sit between 34 and 38 inches. That is why a stair guard may legitimately look lower than the deck guard beside it.
- Baluster spacing no 4-inch openingCRC R321.1.3
- No opening in a guard may let a 4-inch sphere through, from the walking surface up to the required height. On the open side of a stair the limit is 4 3/8 inches, and the triangle under the bottom rail at each step 6 inches.
- Landings Generally at top and bottom of each flight; at least 36 in. deepCRC R318.7.6
- At least as wide as the stair and at least 36 inches in the direction of travel on a straight run. A door opening onto stairs needs a landing; the exception is a door other than the required exit, with two risers or fewer outside, that does not swing over the stairs.
Five ways a deck stair fails inspection
- Using the 36-inch guard height from an out-of-state guideMost national articles quote the international code. California requires 42 inches on the deck, and a rail built to 36 comes down.
- Assuming the old stair can stay as it isWhen the deck is rebuilt, the building department decides whether the stair has to meet the current numbers. The code relaxes it only where the existing space does not allow a shallower stair (CRC R318.7.9). Riser height is where old stairs usually miss.
- A handrail you cannot actually gripA 2x4 laid flat on top of the posts reads as a rail and fails as one. The grip dimension is written into the code for a reason.
- Risers that vary along the flightThree eighths of an inch across the whole flight is the limit. It is also the difference a foot notices in the dark.
- Assuming the city follows the state code exactlyCities may amend it. San Jose, Los Gatos and Saratoga each publish their own handouts, and the building department that issues the permit has the final say.
Who checks this on your project
We build stairs and railings under a California license, class C-61/D41, and the work is inspected by your city, not by us. Our license number is below; the guide to checking it is linked at the end of this page.
- License number
- 1148079
- Classification
- C-61 / D41, Siding and Decking
- Status
- Current and active
- Checked
- September 22, 2026
Questions people actually ask
Is the deck railing height 36 or 42 inches in California?
42 inches on the deck surface. The 36-inch figure comes from the international code used in many other states and from national articles written to it. On the open side of a stair the guard may be 34 inches, and between 34 and 38 where the top rail is also the handrail.
At what height does a deck need a railing?
When the walking surface is more than 30 inches above the grade or floor below, measured within 36 inches horizontally of the open edge. Below that a guard is not required, though many owners add one anyway.
What is the code for stair rise and run?
Rise, the riser height, is 7 3/4 inches maximum (CRC R318.7.5.1). Run, the tread depth, is 10 inches minimum (CRC R318.7.5.2). Within one flight the tallest and shortest riser may differ by no more than 3/8 inch.
What is the handrail height code for deck stairs?
34 to 38 inches, measured vertically from the nosing of each tread (CRC R320.2). A handrail is required on at least one side of any flight with four or more risers (CRC R318.7.8), and it has to be graspable (CRC R320.6): a round Type I rail has an outside diameter of 1.25 to 2 inches; a non-round Type I rail has a perimeter of 4 to 6.25 inches, a cross-sectional dimension no greater than 2.25 inches and edges rounded to a radius of at least 0.01 inch. The code also accepts compliant Type II profiles or equivalent graspability.
What is the baluster spacing code?
No opening in a deck guard may let a 4-inch sphere pass (CRC R321.1.3). On the open side of a stair the limit is 4 3/8 inches, and the triangle formed by the riser, tread and bottom rail may not pass a 6-inch sphere.
Do I need a permit for deck stairs?
Usually yes when the stair is part of new deck work or a replacement, and the answer depends on your city rather than on the state. Ask the building department that would issue it. They decide, and the call is free.
Can I reuse my old stairs on a new deck?
Ask the building department before anyone quotes on it. The code relaxes the stair rules for alterations only where the existing space does not allow a shallower stair (CRC R318.7.9); otherwise expect the current numbers, and older flights most often miss on riser height.
Who is responsible for meeting code, me or the contractor?
The contractor builds to code and the permit is inspected against it, but the property owner carries the consequence of unpermitted or failing work at sale time. Ask in writing who pulls the permit.