Code and standard reference
IRC R311.7 Stair Code
Last reviewed · BuildMath editorial team
IRC R311.7 commonly limits a residential stair riser to 7 3/4 inches, requires at least a 10-inch tread depth, a 36-inch stairway width, and 6 feet 8 inches of headroom, subject to definitions, exceptions, the adopted edition, and local amendments. Measure completed surfaces and verify the full primary code before construction.
Limit table
| Item | Limit or rule | Reference | Verification note |
|---|---|---|---|
| Riser height | Maximum 7 3/4 in | R311.7.5.1 | Check greatest riser and permitted variation. |
| Tread depth | Minimum 10 in | R311.7.5.2 | Measure horizontally between nosings. |
| Stairway width | Minimum 36 in | R311.7.1 | Handrail projections and clear width rules apply. |
| Headroom | Minimum 6 ft 8 in | R311.7.2 | Measure vertically from the sloped tread-nosing line. |
| Landings | At least stair width; 36 in travel direction | R311.7.6 | Door and listed exceptions can apply. |
How to use this code summary
- Confirm which code edition and local amendment applies to the project address.
- Measure the actual completed geometry, not only rough framing or nominal dimensions.
- Compare the calculator output with every relevant row and exception in the primary source.
- Escalate structural, accessibility, egress, guard, and fall-protection questions to the authority or qualified professional.
Calculators that use this reference
ICC Digital Codes: 2021 IRC Section R311.7
Related code references
Frequently asked questions
Is this the complete code text?
No. This is a focused planning summary with a direct primary-source link. Definitions, exceptions, local amendments, and adjacent sections can change how a limit applies.
Which edition should I use?
Use the edition adopted by the authority having jurisdiction for the project address, including local amendments.
Can the calculator certify compliance?
No. It can flag a value against a displayed planning limit, but approval belongs to the authority, designer, or qualified professional.
Why is the source linked?
The source link lets readers and answer engines distinguish a cited rule from an unsupported numerical claim.
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