CodeMandatory
Stair width
IRC R311.7.1Description
Stairways must be ≥36" wide above the handrail, with at least 31-1/2" clear between handrails.
Why this exists
Two adults must be able to pass each other or carry a stretcher up the stairs.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
minWidth | min | 36 | in | |
minBetweenHandrails | min | 31.5 | in |
Categories
Life safetyCirculation
Source
ICCno manifest entry
International Residential Code (2024)
Section: R311.7.1
Published 2024-01-01 · last verified 2026-05-09
Solver enforcement
Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.
Related directives
- Garage / dwelling fire separation · IRC R302.6
- Habitable space minimum ceiling height · IRC R305.1
- Egress window net opening dimensions · IRC R310.2
- Stair riser, tread, and headroom · IRC R311.7
- Smoke alarms required throughout dwelling · IRC R314
Last reviewed 2026-05-09.