Fumes, odors, and gases from your attached garage can find their way into your living space and affect indoor air. Cars, mowers, paints, and lubricants contain or generate substances that can enter your home through open doors, gaps around closed doors, ducts, and other wall and ceiling penetrations. A Canadian study published in 2016 found measurable quantities of benzene (a gasoline-related pollutant) inside houses with attached garages, while finding little in those without a garage. Garage-generated carbon monoxide can even leak into your home and trigger carbon monoxide detectors. Fortunately, you can take a few steps to keep your indoor air quality free of these substances.
What Is Carbon Monoxide?
Carbon monoxide is a colorless, odorless, tasteless gas that forms when carbons in fuel don't burn completely. This gas is highly toxic, poisonous, and deadly in large amounts. Since you can't detect carbon monoxide on your own, it is vitally important to install carbon monoxide detectors in your home.
Equipment / Tools
- Carbon monoxide detector
- Chemical storage locker, plastic bin, or ice chest (optional)
- Spray foam
- Self-closing door and installation supplies
- Drywall finishing supplies
- Exhaust fan
Avoid Trapping Fumes in the Garage
Avoid running your car, motorcycle, chainsaw, lawnmower, or any other gasoline-powered engine any longer than absolutely necessary while in the garage. Never start your car or any other internal combustion engine when the garage door is closed. When you do start the engine after the door has been opened, move it outside as soon as possible, then shut the door to prevent exhaust fumes from floating back into the garage. Shut your car off as soon as possible when you pull it into the garage and leave the door open for a few minutes to allow fresh air in.
When possible, avoid placing mechanical systems such as gas-powered water heaters and furnaces in the garage.
Seal the Gaps
Fumes often find their way into your home through gaps. Assess where there may be gaps from your garage into your home and use inexpensive supplies such as weatherstripping, caulk, and spray foam to address them.
Make sure the door leading from the garage into the house closes tightly and proper weatherstripping is applied. If the weatherstripping is worn, replace it.
Seal all penetrations like ducts and wiring that lead into the house or the ceiling above the garage. Caulk and spray foam are good products for sealing these types of gaps.
Finish the Walls and Ceilings
In new homes, it's not uncommon for the garage to be left with open walls or with drywall attached but the joints not finished. Both these conditions allow garage pollutants to easily find their way inside.
Garage walls and ceilings that are completely covered with drywall, with joints properly sealed with tape and compound, and with the surface primed and painted, are much less likely to allow pollutants into the home. While this will be a larger project, it will pay off in not only protecting your indoor air but also making your garage more attractive and adding to the value of your home.
Most newer homes are required to have a fire rating between garage and living areas. These walls and ceilings are supposed to be fire taped to prevent fire from entering living spaces for a certain amount of time—this taping can also help with insulation.
Employ a Self-Closing Door Into the House
You often find yourself with full arms when you're entering the house from the garage. The result can be that the door remains open until you set the items down. Or maybe you or the kids simply forget to close the door or failed to close it all the way. This can allow nasty fumes from the garage to enter the house quickly and easily. You can avoid this problem by installing a self-closing door.
Store All Chemicals Properly
Make sure all containers of potentially dangerous substances are sealed. Don’t let cans of paint thinner, solvents, and other liquids sit uncovered. If you can smell any chemicals, it means there are fumes in the garage air. Not only are you breathing them in whenever you are in your garage, but they can also enter your home.
When storing a few items, think about getting a plastic bin with a sealable lid or a dedicated ice chest to use to store them. This will provide an additional layer of protection.
If you store many potentially volatile substances in your garage, consider buying a lockable chemical storage cabinet. This will help ensure kids and pets don't access them.
Use an Exhaust Fan
If you spend a lot of time in the garage working with chemicals, paints, wood finishes, combustion engines, or other such items, consider installing an exhaust fan that sends the smells and fumes to the outdoors. A decent bathroom or kitchen fan will be sufficient.
Install Carbon Monoxide Detectors
Make sure your home has at least one carbon monoxide (CO) detector installed. If you're curious about the CO levels in your garage, mount one out there, too, at least temporarily. It might be interesting to see if it goes off on a regular basis. If it goes off when you have not been running your vehicle in the garage, it could be a sign of a dangerous issue with your furnace or gas water heater.
When a carbon monoxide detector sounds the alarm, never ignore it. Immediately ventilate the area and shut off anything that is powered by gas. If you're feeling symptoms of carbon monoxide poisoning, including headache, nausea or vomiting, rapid heart rate, chest pain, confusion, dizziness, shortness of breath, or flu-like symptoms, call 911 or go to the hospital immediately.
Choose a Detached Garage
If you're planning to build a new house or garage, give some thought to making the garage fully detached from the house. You will keep odors, fumes, noise, and fire hazards separate from your main residence.
Mallach, G. et al. Exhaust ventilation in attached garages improves residential indoor air quality. International Journal of Indoor Environment and Health. 2016;27(2). doi:10.1111/ina.12321
Greiner, T.H. Carbon Monoxide Poisoning: Garages. Iowa State University Cooperative Extension.
2018 International Residential Code. International Code Council. 2018.