How To Fix Air Leaks Around a Door
Air leaks around a door can cause drafts and waste energy. A substantial amount of air can leak around an exterior door. Sealing a door with weatherstripping and caulk can increase your home's comfort and reduce heating and cooling costs. Even if your doors already have weatherstripping, you should inspect it every year to make sure it is still performing adequately. Worn out weatherstripping can crack, lose its flexibility and compress to the point that it doesn't effectively seal against the door.
A simple way to determine if your exterior door needs weather striping is to check for daylight coming in around the door. Next take the knob and rattle the door. If it rattles or you can see daylight, air is leaking around your door. Air may also be leaking around the door frame which can be checked with a candle flame or the smoke from a stick of incense. Slowly move the incense along the inside and outside edges of the molding and watch for changes in the movement of the smoke.
Weather stripping should be installed along the sides and top of the door and a door sweep or similar device should be installed on the bottom of the door. Old weather stripping should be periodically replaced. If you press on existing rubber or foam weather stripping and it doesn't bounce back, or you can see dents or tears in the material, it should be replaced.
Weather stripping is available in rubber, foam, plastic and metal. Self-adhesive, staple and nail on are the most common installation types. It is available in a large variety of shapes and sizes also. Choose the shape and size based upon the manufacturers recommendations for your particular installation.
For air leaks that occur around the door frame, they can be sealed by caulking around the the door frame molding. However, the air that gets to the molding may find other ways into your house, so it is best to address the leak at its source.
Ideally you should remove the molding around the door and seal all gaps with non-expanding foam, gap filler rod and caulk. Filling these gaps will prevent air from traveling through the wall and leaking in elsewhere. Also, this air carries moisture that ends up inside the walls potentially leading to moisture damage.
After sealing the gaps around the door frame, replace the molding and seal along its edges with flexible, paintable caulk. Do this both inside and outside your home. Be sure to use exterior caulk for the outside so that it will stand up to the elements.