Footings ≥ 12 in below grade AND below the local frost line (or frost-protected shallow foundation)
2025 RCNYS §R403.1.4 Footing minimum depth + frost protectionDescription
Exterior footings must be placed at least 12 in below the undisturbed ground surface AND below the locally-specified frost line per Table R301.2 — whichever is deeper. Alternatives: a frost-protected shallow foundation per R403.3 (with insulation R-value per air-freezing index), construction per ASCE 32, or footings on solid rock. Free-standing accessory structures under 600 sqft (light-frame) or 400 sqft (heavy) with ≤ 10 ft eave height don't require frost protection.
Why this exists
Frost depth in NY ranges from ~3 ft (Long Island, lower Hudson Valley) to ~5 ft (Adirondacks). Footing below frost stops the freeze-thaw heave that cracks foundations. The Frost-Protected Shallow Foundation (FPSF) option lets architects use a shallow slab with rigid insulation skirts — cheaper than deep footings in challenging soils.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
minDepth | min | 12 | in below grade | Minimum exterior footing depth (regardless of frost) |
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
- Habitable space minimum ceiling height · IRC R305.1
- Wind design · IRC R301.2.1
- Seismic provisions · IRC R301.2.2
- Snow loads · IRC R301.2.3
- Floodplain construction · IRC R301.2.4
Last reviewed 2026-05-15.