Interior stairs: artificial light at ≥ 1 fc on treads + landings; wall switch each floor for ≥ 6 risers
2025 RCNYS §R325.6 Interior stairway illuminationDescription
Interior stairways must have an artificial light source providing at least 1 footcandle (11 lux) measured at the center of treads and landings. For stairs with 6 or more risers, a wall switch must be provided at EACH floor level to control the light. Exception: where remote, central, or automatic lighting is provided. Exterior stairs need a light at the top landing (and bottom for basement exterior access).
Why this exists
1 fc is the threshold for safe foot placement on a stair. The switch-at-each-floor rule prevents fumbling in the dark — a common cause of stair falls. Architects should plan the switch locations into electrical layout; smart-home systems satisfy the rule via automatic / motion-controlled fixtures.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
lightLevel | min | 1 | footcandle | Minimum tread/landing illumination |
switchRiserTrigger | min | 6 | risers | Stair size triggering wall-switch-at-each-floor rule |
Categories
Applies to
- Jurisdiction: New York State
Source
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 2026-05-15.