Difficulty: Moderately Easy
Step1
The space under your front door is the most obvious place to start your investigation. But there are less obvious gaps that can be just as costly. Inspect whereever two different materials meet. Examine all door and window frames as well as bricks, siding, stucco, and foundation. Also look at mail chutes, electrical and gas service entrances, outdoor water faucets. Check where dryer vents or cable, TV and phone lines pass through your walls. If you have central air, make sure the vents and fans fit snugly.
Step2
Shine a flashlight at night over potential gaps while someone helps you from outside. If there are any large cracks, rays of light will shine through. You can't see small cracks this way.
Step3
Shut doors and windows on a piece of paper. If you can pull the paper out without tearing it, you have a leak.
Step4
Depresurize your home (see below).
Depressurize your home
Step1
Turn off your heat on a cold, very windy day.
Step2
Shut all windows and doors.
Step3
Turn on all exhaust fans that blow air outside, such as bathroom and stove vents and fans.
Step4
Light an incense stick and pass it along the edges of potential leak sites. Where the smoke is sucked out of or blown into the room, you have a draft.