Habitable rooms: glazing ≥ 8% of floor area, facing street/yard/court (or 6 fc artificial light)
2025 RCNYS §R325.1.1 Natural lightDescription
Habitable rooms must have an aggregate area of glazed openings of at least 8% of the floor area. The glazing must face a street, alley, public way, or yard/court on the same lot. Roofed porches over the glazing count if the longer side is ≥ 65% unobstructed and ceiling ≥ 7 ft. Sunrooms count too. Alternative: artificial lighting producing at least 6 footcandles (65 lux) averaged at 30 in above the floor.
Why this exists
8% of floor area is roughly the equivalent of one substantial window per 100 sqft of room. The artificial-light alternative is useful in basement bedrooms — but a window remains preferable for daylight quality. Architects should size glazing for both the 8% minimum AND the daylight effect (deeper rooms benefit from higher-placed windows).
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
glazingShare | min | 8 | % of floor area | Glazed-opening area as share of room area |
artificialAlt | min | 6 | footcandles | Alternative artificial light level |
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
- Natural light in habitable rooms · IRC R303.1
- Habitable space minimum ceiling height · IRC R305.1
- Egress window net opening dimensions · IRC R310.2
- Stair riser, tread, and headroom · IRC R311.7
Last reviewed 2026-05-15.