How to find air leaks in your home
To find air leaks, look for cracks and gaps, shine a flashlight over them at night, close a door or window on a sheet of paper, and run a smoke test on a cool, windy day. ENERGY STAR describes all four. Note each gap to seal.
How to find air leaks in your home
Checklist
- Walk the house and look for cracks and gaps at common leak sitesAny season
- Flashlight test: one person outside shining a light, one inside with the lights on, or check from the attic, crawlspace or basementAt night
- Paper test: close a door or window on a sheet of paper and try to pull it outEach window and door
- Smoke test on a cool, windy day (see the safety steps below)Cool, windy day
- Write down each leak so you can seal itAs you go
- For hidden leaks or safety concerns, consider a home energy professionalIf needed
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Look first
ENERGY STAR says a home envelope should be free of gaps and cracks. Start with a visual inspection and note the gaps you see so you can seal them later.
The flashlight test
With a partner outside, have them shine a flashlight over suspected gaps while you stand inside with the indoor lights on. Light showing through marks a leak. You can also check from the attic, crawlspace or basement. Check window and door edges too.
The paper test
Close a door or window on a sheet of paper. If the paper slides out without tearing, air is leaking there.
The smoke test
On a cool, windy day, ENERGY STAR says to turn off gas furnaces and water heaters, close windows, exterior doors and fireplace flues, and run exhaust fans. Then move incense smoke or a powder such as talc or baby powder along common leak points. Smoke or powder that wavers or is pulled toward or away from an opening marks a leak. A damp hand also works, because leaks feel cool.
Turn your furnace and water heater back on when you finish. Never leave burning incense unattended.
When to call a professional
For hidden leaks or safety concerns, ENERGY STAR suggests hiring a home energy professional for a full energy audit.
What you'll need
- WeatherstrippingSeals gaps around doors and windows
- Caulk gunSeals small cracks you find
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Questions
How do I find a draft in my house?
Try the paper test on windows and doors, a flashlight test at night, and a smoke test on a cool, windy day, all described by ENERGY STAR.
What does the paper test show?
Close a door or window on a sheet of paper. If the paper slides out without tearing, air is leaking.
When is the best time to do a smoke test for air leaks?
ENERGY STAR says a cool, windy day. Turn off gas furnaces and water heaters first, close windows, exterior doors and fireplace flues, and run exhaust fans.
How do I do the flashlight test for air leaks?
With a partner outside shining a flashlight over suspected gaps and the indoor lights on, light showing through marks a leak. You can also check from the attic, crawlspace or basement.
Is there a way to check for hidden leaks?
ENERGY STAR suggests a home energy professional and a full energy audit for hidden leaks or safety concerns.
Sources
Related guides
General guidance for typical homes. Follow your equipment manufacturer's instructions and local codes, and hire a pro for anything you're not comfortable doing.