Why garage separation matters
Garages hold cars, fuel and chemicals, so the code requires a fire-resistant separation between an attached garage and the living space. Plans that don't show it get the classic comment: “Provide garage/dwelling separation per IRC R302.6.”
Drywall requirements (IRC R302.6)
| Where | Typical minimum |
|---|---|
| Walls between garage and house (and attic) | ½″ gypsum board on the garage side |
| Garage ceiling with habitable rooms above | ⅝″ Type X gypsum board |
| Structure supporting that ceiling | ½″ gypsum board or equivalent |
| Detached garage within 3 ft of the house | ½″ gypsum on the interior side of exterior walls in that zone |
Local amendments sometimes require more, such as Type X on all separation walls.
The door between garage and house (IRC R302.5.1)
- No opening directly into a sleeping room from the garage.
- Door must be solid wood or solid/honeycomb-core steel at least 1⅜″ thick, or 20-minute fire-rated.
- Many code editions and jurisdictions also require it to be self-closing and self-latching.
Ducts and penetrations (IRC R302.5.2–R302.5.3)
- Ducts that pass through the separation must be at least 26-gauge steel (or other approved material) and have no openings into the garage.
- Penetrations for pipes, wires and vents must be sealed with approved material to keep the separation intact.
- Garage floors must be noncombustible and slope toward a drain or the vehicle door.
Compare costs, separation requirements and resale impact before you decide.
Compare optionsWhat to show on the plans
- A note or wall-type tag on the common wall and ceiling: gypsum type and thickness, garage side.
- The house door specified: solid-core/steel 1⅜″ or 20-minute rated, self-closing where required.
- Duct routing noting steel ducts with no garage openings.
- Penetration sealing note.
This is a quick drafting fix. Our Permit Correction Service adds it with every other drafting comment in your letter — $499 flat. Also see CO alarm rules, which apply when a garage is attached.
Garage conversions and bonus rooms over the garage
Converting part of a garage or building a room above it changes the separation: a bonus room above needs the ⅝″ Type X ceiling, and a partial conversion needs a full separation wall with the proper door. More in garage conversion plans and changing the garage on a house plan.
Frequently asked questions
What drywall is required between a garage and a house?
Under the IRC, commonly ½-inch gypsum board on the garage side of the separating walls, and ⅝-inch Type X on the garage ceiling when there are habitable rooms above. Local amendments may require more.
Does the door from the garage to the house need to be fire-rated?
It must be solid wood or solid/honeycomb-core steel at least 1⅜ inches thick, or 20-minute fire-rated. Many jurisdictions also require it to be self-closing and self-latching.
Can a garage door open into a bedroom?
No. The IRC prohibits openings from a garage directly into a sleeping room.
Can HVAC ducts run through the garage wall?
Yes, if they are at least 26-gauge steel (or other approved material) with no openings into the garage.
Can you fix the garage separation comment on my plans?
Yes — we add the separation notes, wall types and door specification as part of our $499 Permit Correction Service.