Roof live load: 20 psf flat/low-slope; 16 psf medium-slope; 12 psf steep
2025 RCNYS §R301.6 Minimum roof live loads (Table R301.6)Description
Roofs must be designed for the live load listed in Table R301.6 OR the ground snow load, whichever is greater. Minimum live loads (for tributary areas 0-200 sqft): 20 psf on flat or low-slope roofs (rise < 4:12), 16 psf on medium-slope roofs (4:12 to <12:12), 12 psf on steep roofs (12:12 and steeper). Larger tributary areas reduce the per-sqft load. In snow-load areas (most of NY), the snow load typically dominates.
Why this exists
Roof slope changes how loads accumulate. Flat roofs hold snow and water; steep roofs shed both. The Table R301.6 numbers are the floor for engineering; the ground snow load from Table R301.2 supersedes when greater. NY's ground snow load varies from 20 psf (Long Island) to 90 psf (high Adirondacks) — architects must pull the local value before sizing rafters.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
flatRoof | min | 20 | psf | Flat or rise <4:12 (tributary 0-200 sqft) |
mediumRoof | min | 16 | psf | Rise 4:12 to <12:12 |
steepRoof | min | 12 | psf | Rise 12:12 and greater |
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.