Attached Garage Fire Containment
Why are garages (both attached and detached) fire hazards?
- Oil or gasoline can drip from cars. These fluids may collect unnoticed and eventually ignite.
- Flammable liquids, such as gasoline, oil and paint, are commonly stored in garages. Some other examples are brake fluid, degreaser, motor oil, varnish, lighter fluid, and fluids containing solvents, such as paint thinner. These chemicals are flammable in their fluid form, and some may create explosive vapors.
- Heaters and boilers, which are frequently installed in garages, create sparks that can ignite fumes or fluids. Car batteries, too, will spark under certain conditions.
- Mechanical or electrical building projects are often undertaken in the garage. Fires can easily start while a careless occupant is welding near flammable materials.
The 2006 edition of the International Residential Code (IRC) states the following concerning doors that separate garages from living areas:
R309.1 Opening Penetration
Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and the residence shall be equipped with solid wood doors not less than 1-3/8” (35 mm) in thickness, solid- or honeycomb-core steel doors not less than 1-3/8” (35 mm) thick, or 20-minute fire-rated doors.
In addition, InterNACHI inspectors can check for the following while inspecting doors that separate garages from living areas:
- While not required by the IRC, it is helpful if there is at least one step leading up to the door from the garage. Gasoline fumes and other explosive gases are heavier than air, and they will accumulate at ground level. Their entry beneath a door will be slowed by an elevation increase.
- Doors should have tight seals around their joints to prevent seepage of fumes into the living areas of the house. Carbon monoxide, with the same approximate density as air (and often warmer than surrounding air), will easily rise above the base of an elevated door and leak through unsealed joints.
- Doors should be self-closing. Many homeowners find these doors inconvenient, but they are safer than doors that can be left ajar. While this requirement is no longer listed in the IRC, it is still a valuable recommendation.
- If doors have windows, the glass should be fire-rated.
- Pet doors should not be installed in fire-rated doors. Pet doors will violate the integrity of a fire barrier.
Walls and Ceilings
The requirements below are from the 2012 IRC.
- Minimum ½” gypsum board or equivalent on garage side of walls and ceilings common to house or shared attic space
- Minimum 5/8” Type X gypsum board or equivalent on ceiling under a habitable room such as a bedroom.
- Minimum ½” gypsum board or equivalent on walls, beams, or other structures that support ceilings providing separation between house and garage
- Garage walls that are perpendicular to adjacent dwelling unit wall are OK to be unprotected unless they are supporting floor/ceiling separations.
- No direct openings between the garage and sleeping rooms.
- Openings between the garage and residence shall be equipped with solid wood doors not less than 1 3/8” thickness, solid or honey-comb-core steel doors not less than 1 3/8” thick, or 20-minute fire-rated doors, equipped with a self-closing device.
- Ducts in garage and penetrating common walls shall be minimum 26-guage steel
- No duct openings in the garage
- Penetrations of common walls shall be sealed with an approved material (e.g., caulk, putty, or sealant). Fire blocking around chimneys and fireplaces must be noncombustible. Sealant around vents, pipes, ducts and wires at the ceiling and floor level can be constructed from combustible materials. All fire blocking material must be securely fastened in place.
- Detached garages located less than 3 ft. from a dwelling unit on the same lot requires ½” gypsum board on interior side of garage walls facing the house.
- Information provided from the Complete Code Check and AHIT
General safety tips that inspectors can pass onto their clients:
- Use light bulbs with the proper wattage.
- Do not overload electrical outlets.
- Tape down all cords and wires so they are not twisted or accidentally yanked.