Stair headroom at least 6 ft 8 in measured from tread nosing
2025 RCNYS §R318.7.2 Stairway headroomDescription
Stairway headroom must be at least 6 ft 8 in, measured vertically from the sloped line adjoining the tread nosing or from the floor of a landing or platform. Where tread nosings extend under the edge of a floor opening through which the stair passes, the floor opening may project horizontally into the required headroom by no more than 4¾ in.
Why this exists
Headroom failures are the most common stair-design mistake architects make at the bottom of a stair landing or at a switchback. The 4¾ in nosing exception saves the design when the upper floor is exactly at the stair's top — but the architect has to check it explicitly.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
headroom | min | 6.667 | ft (6'8") | Vertical clearance from nosing line |
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.