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Building Code Reference

Got a CRC R318.7.5 correction?

Stair riser and tread dimensions

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CRC R318.7.5 sets the dimensional limits for stair risers and treads in California residential construction. Maximum riser height is 7-3/4 inches; minimum tread depth is 10 inches. The trickiest part of the rule: within any single flight, the tallest riser cannot exceed the shortest by more than 3/8 inch, and the same uniformity cap applies to tread depths. That 3/8-inch tolerance is what catches most corrections.

How to fix it

  1. Add a stair section or detail to the plans

    The quickest fix for a first-time R318.7.5 correction is adding a clear stair detail. Draw or annotate a section through the stair showing each riser height and tread depth with dimensions. This can go on the building section sheet or a dedicated stair detail at 1/4"=1' or larger. Confirm the detail is labeled by sheet and detail number so the plan-checker can find it in the index.

  2. Confirm riser height does not exceed 7-3/4 inches

    Measure from finish floor to finish floor across the run and divide by the number of risers to get your target riser height. That number must be 7-3/4 inches or less. If your calculation puts you slightly over, you have two options: add one more riser to the run, or lower the overall rise slightly if the landing elevation allows it. Note the finish floor materials in your calculation; 3/4-inch hardwood or thick tile can push a borderline riser over the limit.

  3. Confirm tread depth is at least 10 inches

    Tread depth is measured horizontally between the leading edges (nosings) of adjacent treads, at a right angle to the tread's leading edge. R318.7.5.2 requires a minimum of 10 inches. For a typical residential stair this is straightforward, but watch for winder stairs or tapered treads at a turn, where the tread must still be 10 inches deep at the walkline, 12 inches from the inside of the turn, and at least 6 inches deep at any point.

  4. Verify the 3/8-inch uniformity tolerance across all risers

    Calculate or field-verify every riser height in the flight. Find the tallest and shortest. If the spread is more than 3/8 inch, the stair does not comply. This often shows up when framing members are slightly different thicknesses, or when a top or bottom riser is adjusted to meet a finished floor level. Fix it by adjusting framing or by specifying a self-leveling topping at the landing. Document in the plans how uniformity will be held.

  5. Check tread depth uniformity by the same 3/8-inch rule

    The same spread cap that applies to risers also applies to tread depths within a flight. If one tread is 10 inches and another is 10-1/2 inches, that 1/2-inch spread exceeds 3/8 inch and triggers a violation. For wood-framed stairs, tread depth is controlled by the stringer layout, so confirm the stringer is cut consistently. Note the expected tread depth range on the stair detail.

  6. Address finish materials in the riser and tread callout

    Plan-checkers flag corrections when the finish material is not called out, because tile, hardwood, and concrete toppings change the effective riser height and tread depth (carpets, rugs and runners are excluded from stair dimensions). On your stair detail or in the notes, specify the finish material and its thickness. If the rough framing puts the bottom riser at 7 inches and you add 3/4-inch hardwood to the treads but not the floor below, the finished bottom riser is 7-3/4 inches, which is exactly at the limit. Note it explicitly so the plan-checker does not have to guess.

  7. For retained existing stairs, add a scope clarification note

    If the permit includes a stair that predates current code and you do not want to rebuild it, add a clear note on the plans stating the existing stair is outside the scope of work and is not being altered. Some plan-checkers will accept this for a partial remodel where the stair is not touched. If the scope triggers a whole-building review or if the stair connects new and old space, you may need to bring the stair into compliance or obtain a variance.

  8. Resubmit with a written response to each correction item

    When you resubmit, attach a correction response letter that lists each flagged item by number and explains where on the revised plans it has been addressed. For R318.7.5, note the sheet and detail number where the stair dimensions are now shown. Plan-checkers work faster when they can go directly to the fix without hunting through a full set of revised sheets.

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Why you got flagged

Plan-checkers flag R318.7.5 corrections for a handful of predictable reasons.

The most common is a simple omission: the building section shows a stair, but no riser height or tread depth dimensions are called out anywhere on the plans. Plan-checkers cannot assume compliance, so they flag it and send the package back. Adding a callout or a stair detail with the actual dimensions is usually all it takes.

The second scenario involves the uniformity tolerance. A contractor frames a stair run with wood framing and the subfloor finish or a landing transition causes one or two risers to land slightly different from the rest. If the as-built spread between the tallest and shortest riser exceeds 3/8 inch, it is a code violation even if every individual riser is under 7-3/4 inches. Plan-checkers on second or third submittals sometimes specifically ask for a note or framing detail confirming how the contractor will hold uniformity.

The third scenario is an ADU or interior remodel where an existing stair is being retained. If the scope of work triggers a full R318 review and the existing stair has riser heights from an older construction era, like 8-inch risers common in pre-1980 homes, the plan-checker will flag R318.7.5 even if the contractor did not touch the stairs. The correction asks either for a code-conforming stair or a written scope clarification showing the existing stair is outside the permit scope.

The official code

California Residential Code R318.7.5 — Stair Riser Height and Tread Depth, 2025 Edition

Read the source →

Common questions

Does the 3/8-inch uniformity rule apply to each flight separately or the whole stairway?
It applies within each individual flight. A flight is an uninterrupted run of stairs between two landings or between a floor and a landing. If your stairway has two flights with a landing in between, R318.7.5 evaluates the uniformity tolerance within each flight independently. So the tallest riser in flight one must be within 3/8 inch of the shortest riser in flight one. The two flights do not have to match each other, only internally.
What counts as tread depth under CRC R318.7.5?
Tread depth is measured horizontally from the face of one riser to the face of the next riser. The nosing overhang is not counted as part of the 10-inch minimum tread depth, but CRC R318.7 also specifies nosing requirements separately. The key dimension to verify is the 10-inch minimum from riser face to riser face. For stairs with no vertical riser (open stairs), the measurement is from the leading edge of one tread to the leading edge of the next.
Can I get a variance for a steeper stair in a tight ADU or garage conversion?
Variances from stair dimension requirements are technically possible but rare and jurisdiction-specific. The concern is life safety: steep risers and inconsistent tread depths cause falls. Most cities in California will not grant a variance for the riser height cap. A more common approach is a space-saving or alternating-tread stair for attic or loft access, which has its own set of requirements under CRC R318.7.10. For primary means of egress, the standard R318.7.5 dimensions apply without exception in most jurisdictions.
Does R318.7.5 apply to exterior stairs and decks?
Yes. CRC R318.7.5 applies to all stairways serving residential occupancies, including exterior stairs at decks, porches, and yard access. The same 7-3/4-inch maximum riser height, 10-inch minimum tread depth, and 3/8-inch uniformity tolerance apply. The gotcha on exterior stairs is that the first riser at grade can end up short or tall depending on how the grade slopes away from the house, which throws off the uniformity. Specify the finish grade elevation at the bottom landing on your site plan.
My stair has a partial landing mid-flight. Does that restart the uniformity tolerance?
A landing restarts the flight count. Once a full landing is reached, the next run of stairs is a new flight and R318.7.5 evaluates uniformity within that new flight. However, an intermediate nosing or a single step that does not meet the full landing dimensions under R318.7.6 is not a landing; it is just part of the flight, and the 3/8-inch tolerance runs through it without resetting. Make sure any mid-run level change qualifies as a code-compliant landing or it will not reset the tolerance.
How do I show stair dimensions on plan check submittal sheets?
The clearest approach is a cross-section detail through the stair at 1/4"=1' or larger showing: each riser height with a dimension, total rise with a dimension, tread depth with a dimension, nosing profile and size, and finish floor material noted with thickness. Label the detail with a sheet reference and detail bubble. Also add a note on the floor plan sheet pointing to the stair location and referencing the detail. If the plan-checker has to hunt for stair dimensions, the correction comes back. Make it easy to find.

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