Tips to finding and sealing an air leak

Before you can seal an air leak, you need to find out where it is! These tips will help you find and then fix an air leak.

• On a windy day, light a stick of incense and move it slowly alongside doors where outside air might enter. When the incense smoke moves horizontally, you've found a leak that may require weather stripping, caulking or sealing.
• You can also detect drafts by feel. Dampen the back of your hand and move it along the perimeter of exterior doors and windows; you'll feel coolness when air is coming through.
• In addition to the wear and tear of ordinary use, the weather stripping around exterior doors will shift as your house shifts and settles. Check the weather stripping around these doors once a year to see if it needs to be adjusted or replaced.
• When it's time to replace a worn threshold gasket, take the old one with you to the hardware store to ensure a good match. A gasket has two splines (narrow, projecting strips) that fit into grooves in the threshold; these may tear off and stay in place as you remove the old gasket. If so, use a narrow screwdriver to pry the splines out, and make sure no pieces remain in the grooves. To install a new gasket, press its splines into the grooves using your fingers, then push down with a wood block to complete the job.

• Here's a rule of thumb for determining whether air is leaking around an inside window or its storm window: if moisture forms on the windowpane, cold air is leaking past the storm sash. If condensation appears on the storm window, warm air is leaking around the inside window.
• When applying self-adhesive weather stripping to windows, start with a clean, dry surface. Any residual moisture, dirt, or oil will prevent the adhesive from adhering to the frame and forming a tight seal. If the area is dusty or grimy, use a small amount of rubbing alcohol on a cloth or paper towel to clean it off. Use a hair dryer on its highest setting to thoroughly dry the surface and remove trapped moisture. Before installing weather stripping on a door, check that none of the hardware is loose and that the door latches tightly.
• When selecting weather stripping, be sure to compare cost to durability. Felt is very inexpensive, for example, but it is also one of the least durable and least effective types of weather stripping.