IRC R302.6 - Fire Separation Requirements Between a Garage and Living Space

The drywall in your garage is not just a finish surface. It is a fire separation assembly required by code. IRC R302.6 and its Table R302.6 specify exactly which assemblies are required, depending on what is on the other side of the wall or ceiling.

What this section says

IRC R302.6 requires that the garage be separated from the dwelling by the assemblies listed in Table R302.6. The main requirement is:

"The garage shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5."

Table R302.6 lists four separation scenarios with different gypsum board requirements.

Garage wall facing the residence. The garage side of the common wall must have not less than 1/2-inch gypsum board applied to the garage-facing surface.

Habitable rooms above the garage. The floor-ceiling assembly under a habitable room above the garage must have not less than 5/8-inch Type X gypsum board.

Structures supporting habitable rooms above. The framing and structure that supports habitable rooms over the garage must be protected with not less than 1/2-inch gypsum board.

Adjacent dwelling units (within 3 feet). When a garage is located less than 3 feet from a dwelling unit on the same lot, the interior side of the exterior garage wall within that distance must have not less than 1/2-inch gypsum board.

The code also notes that the wall separation requirement does not apply to garage walls that run perpendicular to the adjacent dwelling unit wall. This exception simplifies construction at certain configurations.

When it applies

R302.6 applies to attached garages in residential construction where the IRC is adopted. Denver's 2025 Building Code is based on IRC 2024; R302.6 applies in Denver.

Any work that disturbs the garage-to-house wall or ceiling assembly requires maintaining or restoring compliant fire separation. This includes installing new opener wiring, HVAC penetrations, and structural modifications.

The section works with R302.5 (doors and penetrations) to create a complete fire separation. Both sections apply simultaneously.

What this means for you

Half-inch drywall on garage walls is the baseline. A common garage wall with living space on the other side needs 1/2-inch drywall on the garage side. Unfinished garage walls that share a wall with the house are a code deficiency.

A bedroom or living room above the garage requires Type X. The 5/8-inch Type X requirement is more demanding than the standard wall requirement. Type X is a denser, fire-resistant gypsum product. If you have finished space above your garage, verify the ceiling assembly uses the correct material.

Any penetration must be sealed. Wires, pipes, and ducts punched through the fire separation wall must be fire-stopped with code-approved materials. Open penetrations defeat the fire separation.

Denver permit inspections include this check. When work is permitted in the garage or at the house-garage connection, the AHJ inspector verifies the fire separation assembly.

G Brothers routes opener wiring through the fire separation wall during installations. We maintain fire-stopping at all penetrations and can point out visible deficiencies in the separation assembly.

Full text and source

Read IRC R302.6 and Table R302.6 at https://up.codes/s/dwelling-garage-fire-separation. The 2025 Denver Building Code is based on IRC 2024 and is available at denvergov.org.

IRC R302.6 applies to attached garages. Local jurisdictions may adopt amendments that modify the gypsum board thickness or Type X requirements. Confirm with your local AHJ before construction.