Fire Separation Between an Attached Garage and the House

A garage attached to a house stores fuel-burning vehicles and often gasoline, solvents, and other combustibles, so codes require a fire-rated separation between the garage and the rest of the house — a rated wall assembly, a self-closing door with its own fire rating, and attention to how ductwork and penetrations through that wall are sealed.

Where living space sits directly above a garage, the required fire-resistance rating typically increases, since a fire starting below has less time before it threatens an occupied space. It's also common for codes to require the garage floor to be sloped toward the door or a drain, partly to control spilled fuel and exhaust rather than letting them pool against the shared wall.