IRC R302.5 - Door and Opening Requirements Between a House and an Attached Garage

The door between your house and your attached garage is a life-safety element. It is the last line of defense if a fire or carbon monoxide event begins in the garage. IRC R302.5 specifies exactly what that door must be and how it must function.

What this section says

IRC R302.5 governs all openings and penetrations in the wall separating an attached garage from the dwelling.

IRC R302.5 states the main rule:

"Openings in garage walls shall comply with Section R302.5. Openings from a private garage directly into a room used for sleeping purposes shall not be permitted."

For the door between the garage and the living space, the code requires one of the following:

• A solid wood door at least 1-3/8 inches (35 mm) thick
• A solid or honeycomb-core steel door at least 1-3/8 inches thick
• A 20-minute fire-rated door assembly

The door must be self-closing and self-latching. A simple door without a self-closing device, or a door held open by a prop or a hook, does not comply.

The code also prohibits any door between a garage and a bedroom. A garage-to-bedroom door would not comply regardless of its rating.

For penetrations in the garage wall (pipes, conduit, wires), the section requires that openings be protected in a manner that maintains the fire-separation rating of the wall assembly. Unprotected pipe penetrations are a common deficiency found during home inspections.

When it applies

R302.5 applies to new construction and to alterations involving the garage-to-house connection. It applies everywhere the IRC has been adopted, which includes most of Colorado. Denver's 2025 Building Code is based on the IRC 2024 with local amendments; R302.5 requirements apply in Denver.

This section works alongside R302.6, which requires the garage wall and ceiling assembly itself to be separated from the dwelling. R302.5 governs the door and openings in that wall.

If a homeowner replaces the door between the garage and the house during a remodel, the new door must meet R302.5 requirements. A building permit for work in this area will require an inspection of the door assembly.

What this means for you

Check the door you have. The required door is heavier than a standard interior door. You can identify a compliant solid-core door by weight (it feels substantial when you open it) and by label (fire-rated doors carry a label on the hinge edge showing the rating and manufacturer).

The closer is not optional. A self-closing device (a hydraulic closer mounted at the top of the door) is required. Many homeowners remove or disable these because the door slams shut. If the closer is missing, the door fails to comply.

Gaps fail the standard. The self-latching requirement means the door must fully close and latch on its own, every time. A door with a damaged latch or a misaligned strike plate that stays slightly open does not comply.

Denver inspectors check this. On any permit that includes work in the garage or at the garage-to-house connection, the AHJ inspector will verify the door rating and the self-closing hardware.

G Brothers does not perform door installations, but we flag non-compliant garage-to-house doors when we observe them during opener or door service visits.

Full text and source

Read IRC R302.5 at https://up.codes/s/dwelling-garage-opening-and-penetration-protection. The 2025 Denver Building Code is based on IRC 2024 and is available at denvergov.org.

IRC R302.5 applies to attached garages. Detached garages are not required to meet this section. Consult your local AHJ for any local amendments to the door-rating requirement.