Garage / dwelling fire separation
IRC R302.6Description
Walls and ceilings between an attached garage and the dwelling must be separated by at least 1/2-inch gypsum board on the garage side. Doors between the garage and habitable rooms must be solid-core or 20-minute fire-rated, self-closing.
Why this exists
A car fire in an attached garage can flash to ignition temperature in under five minutes. The fire-rated wall + door buys time for occupants to escape — this is one of the most important codes in the IRC.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
minWallSeparation | min | 0.5 | in | Minimum gypsum board thickness on the garage side. |
minDoorRating | min | 20 | min | Minimum fire-rating in minutes for the door (or solid-core 1-3/8" thick). |
Categories
Applies to
- Room types: garage
- When:
- attached garage only
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.
Backed by research
Walls and ceilings between an attached garage and the dwelling must be separated by at least 1/2-inch gypsum board on the garage side. Doors must be solid-core or 20-minute fire-rated, self-closing.
Council (2024), ICC — R302.5, R302.6 — view source ↗
See the full research bibliography for context. Our licensing principle describes how we cite published research without using the underlying datasets.
Plan symbols this applies to
These plan symbols invoke this directive when placed on a floor plan. Click any to see where it's drawn and what other rules apply to it.
Related directives
- 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
- Carbon monoxide alarms in sleeping areas · IRC R315
Last reviewed 2026-05-09.