Is Carbon Monoxide Coming from Your Garage?

Written by Anita Alvarez
Updated June 17, 2013
faux wood garage door
The danger of carbon monoxide may be seeping into your home from the attached garage. (Photo courtesy of Angie’s List member Chris W., Penndell, Pennsylvania)

Is a carbon monoxide catastrophe lurking in your garage?

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Known carbon monoxide (CO) risks include by-product emissions from a gas furnace or stove located inside your home. But dangers may be lurking in your attached garage, too.

Often, CO released from a running vehicle enters the home when someone simply opens the door. CO poses significant risks to the health of home occupants, causing problems ranging from headaches to flu symptoms, even death. Other times, the season and the seal of the shared wall create conditions that make CO seepage into the home more likely.

The proof

A study by the Canada Mortgage Housing Corporation shows that homes with attached garages have much higher CO concentrations than homes without, turning a convenient, must-have garage into a deadly weapon.

The unavoidable reality of CO emissions from a car are not the only factor that increase concentrations of it in a home. Weather conditions also contribute, and two factors make it possible:

• Air movement. The wall of a garage (and perhaps the ceiling if the home is positioned above it) can weaken over time, developing tiny cracks and crevices that allow air and any CO present to move into the home. Further tests conducted by the CMHC revealed that significant leaks occur in the shared house-to-garage wall and is no less prone to leakage than rest of the home's structure.

• Pressurization. Colder weather scenarios make the possibility of CO movement even more likely. As the temperature drops and homeowners run their vented heating systems, the home becomes depressurized. Even in mild climates and temperatures, running exhaust fans can cause the home's pressure to drop, too. Once the home is depressurized or it holds a lower pressure than the outdoors, the force of the pressure pulls outside air (and higher-pressured air that exists in a garage) into the home, bringing any CO that exists in the garage air along with it.

RELATED: Protect Your Family from Carbon Monoxide Risks

Preventing carbon monoxide dangers

The best course of action when dealing with carbon monoxide safety involves using a multi-pronged approach:

• Use CO detectors. Position a detector close to the garage-to-home door so that it can alert you to CO that moves in through an open door. If you have a two-story home, install a detector on the second floor, too.

• Seal up the walls connecting the attached garage to the home. For best results, hire an energy auditor who will employ specialized tools to precisely locate air leaks. You'll be glad you did, knowing that the garage is tightly sealed and CO won't move through nearly invisible cracks and leaks.

• Install an exhaust fan in the garage. Running it via a timer every time you start up the car and pull out of the garage or return to the home and shut the car off ensures that CO is exhausted from the garage. The exhaust fan brings the pressure down in the garage, too, creating an equilibrium between the garage and the home, putting a stop to air movement.

• Replace weatherstripping. Regularly do this around the garage-to-home door, ensuring a tight seal.

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