Following is an excerpt from the book Back to Basics by Abigail R. Gehring. Click here to purchase a copy of this book from Amazon.

Every house has gaps and cracks through which outdoor air can enter and indoor air escape. In most houses air exchange takes place at a rate of one to two changes in an hour. Inevitably, this turnover of air causes a substantial loss of heated air in wintertime.

Caulking and weather stripping are the basic means for reducing this loss. Properly applied, they can lessen the air exchange rate by 50 percent and cut fuel bills by 5 to 20 percent, depending on how leaky your house is.

Caulking is used to seal construction cracks in the body of the house, such as those between window frame and siding. The usual way to apply caulking is with a caulking gun loaded with a cartridge of caulking compound. When the trigger is pressed, a continuous bead of compound is squeezed out, like toothpaste from a tube. The compound is also sold in a rope like strip that can be pressed into place. Caulking is not a modern development. In pioneer days homesteaders would plug leaky cabins with such materials as moss, mud, clay, and pitch-impregnated rope. Today’s caulking compounds are superior. They are easier to apply, last longer, and insulate better. Oil-based compounds are still very common. Others include acrylic latex types that permit cleanup with water before they set. Butyl compounds are more flexible and stick to more materials.

Weather stripping is used to seal gaps between moving parts, such as those between a window sash and frame, and at door closures. To minimize wear, match the weather stripping to the motion of the parts. For compressive contact, as in a door closing, use felt or foam. For a sliding motion select a tough plastic or metal strip. Whatever type you buy, be sure it is thick enough to fill the gap. Foam stripping is available with a wood backing or with a self-stick adhesive backing. Where considerable compression is likely, as in a front door closure gap, use an open-cell foam, such as urethane. For light compression use a closed-cell type, such as vinyl. Adhesive-backed weather stripping bonds best when the temperature is above 50°F. During cold weather warm the surface to which the stripping is to be applied with a heat lamp or hair dryer. In some cases inexpensive felt stripping can be used for sliding as well as compressive contact. Where sliding motion is involved, the felt must be mounted carefully so that contact pressure is adequate but not excessive, since friction shortens the felt’s useful working life. Felt stripping is usually held in place by tacks or staples. Wherever possible, with any type of stripping, make a trial fit with a short length before doing the complete job. Check that the seal is snug enough to block drafts but not so tight that the window cannot open or the door catch fail to hold.