Why do garages need to be fireproofed?

expert EXPERT April 26, 2007

Attached garages pose a fire hazard to houses. They also pose a life safety hazard in that the exhaust fumes from automobiles are toxic, usually containing carbon monoxide. Building authorities call for fire- or gas-proofing of garage/house walls, depending on your area. Fireproofing of walls and ceilings is required in the United States. In Canada, gas-proofing is called for on walls and ceilings of garages attached to single-family homes.

Ceilings only have to be dealt with if there is living space above, or if fumes could enter living spaces from above the garage ceiling. You should be familiar with what your local building authorities require.

If you are building an attached garage , find out what the authorities will accept in your area and how most builders accomplish it. Are concrete block walls required between garages and houses? Are wood-frame walls allowed? What sort of drywall treatment is necessary to get the required fire rating? Is fire-rated drywall typical? Do drywall joints have to be taped? Are noncombustible studs used? How are ceilings with living space above handled? Is the required fire rating the same? How is it typically achieved?

If you already have an attached garage, check your fireproofing or gas proofing. Ineffective fire- or gas-proofing may exist because of

• poor design or construction practices originally (including missing components or inappropriate materials)
• mechanical damage (often a result of vehicle impact in garages)
• moisture damage

Compromised fire- or gas-proofing is a life safety issue. A fire in the garage may spread to the house, or toxic fumes from automobile exhaust may enter the living quarters.

As you go into the garage, be clear as to exactly what parts of the garage connect to living space. Is it one wall, two walls, three walls? Is it all or part of the ceiling? Look for areas where the tightness of the wall may have been breached or where inappropriate materials have been used.

Be careful if there is ductwork from a forced-air system passing through the garage. There should be no gaps in the ductwork where automobile fumes could enter the house, and there should be no supply or return registers. Additionally, ductwork in garages should be insulated to the level required in your area.