Guards required where walking surface is >30 in above floor below; 36 in tall; 4 in sphere rule
2025 RCNYS §R321.1 Guards — where, height, opening limitDescription
Guards must be provided on open-sided walking surfaces (floors, stairs, ramps, landings) located more than 30 in above the floor or grade below within 36 in horizontal of the open edge. Guards must be at least 36 in tall (34 in on the open side of a stair, measured from a line connecting the tread nosings). Openings within the guard must not allow passage of a 4-in-diameter sphere (4⅜-in sphere on the open side of stairs; 6-in sphere only at the triangular opening formed by riser/tread/bottom rail). Insect screening is NOT a guard.
Why this exists
The 30-in height triggers a guard at most deck rim joists, second-story floor edges, and stair landings. The 4-in sphere rule is the kid-safety standard adopted from playground equipment. Decks more than 30 in above grade are the most common owner-built code violation; surface this rule early in the schematic if a deck is in the program.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
triggerHeight | min | 30 | in | Walking-surface height above lower grade triggering guard |
guardHeight | min | 36 | in | Guard minimum height |
stairGuard | min | 34 | in | Stair-side guard minimum height |
spherePass | max | 4 | in | Maximum sphere passing guard openings |
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.