Home Improvement : Protecting Door Cracks Against the Elements : Weatherstripping: Installation on outside doors cuts flow of cold or hot air and saves on energy costs.

Ever stand near an unweatherstripped door on a cold day or night? Chances are you noticed how much colder that part of the house felt.

And when the wind blows, you can actually feel the cool air passing around the edges of the door into the room.

Energy conservation experts advise that installing weatherstripping on outside doors can go far toward reducing household energy costs.

“Unweatherstripped exterior doors result in winter heating and summer cooling bills significantly higher than necessary for thousands of Southland homeowners and renters,” said Bill Warren,Southern California Gas Co. representative.

What many of homeowners and renters do not realize is how simple it can be to install weatherstripping. Most doors can be done by a novice in about an hour.

The easiest way to do it is to follow this two-part procedure:

First, attach a device called an “automatic door sweep” to the bottom outside edge of the door. Once that is in place, install a product called “jamb-set weatherstripping” to the jamb around the perimeter of the door.

An automatic door sweep consists of a spring-loaded aluminum strip with a soft vinyl edge that drops down as the door closes to form a seal against the threshold and lifts up to clear the threshold when the door is opened. It is attached to the outside of the door just above the bottom.

Sweeps come in brown, white, gray and dull brass. Most makes are for doors up to 36 inches wide, but sweeps for doors up to 42 inches are available.

When the door is opened, the vinyl edge automatically lifts up to clear the threshold and most interior floor coverings.

As the door is shut, the vinyl edge drops to form a tight seal against air, water, dust, snow and insects and allows you to close gaps under the door up to one-half inch. It easily attaches without adjusting or planing the door or removing the door from the hinges.

Automatic door sweeps are sold in most major builder’s hardware and supply stores. If your local store does not carry them, odds are they can order them for you. Call first to save time.

The first step toward installing the mechanism is to do a little measuring.

Locate the “door-stop molding” along the top and the left and right sides of the door jamb. Running a measuring tape along the threshold, measure the distance between the door stop molding on the left and the door stop molding on the right.

Cut the door sweep one-eighth of an inch shorter than this measurement with a hacksaw.

Step outside and shut the door. Center the door sweep between the door stop molding on the left and the door stop molding on the right. Attach it to the outside lower edge of the door about 2 1/4 inches above the threshold with the screws provided.

To make driving the screws into the door easier, first drill 1/16-inch “pilot” holes about one-half inch deep into the door where the screw holes across the top of the sweep indicate. If you do not have a drill, use a hammer and nail to make the holes.

Inside the small bag containing the screws is a plastic sleeve about one-quarter inch long called a “stop.” Also, there is one screw that is longer than the others.

Thread the large screw through the stop and attach it to the non-hinged side of the jamb so the sweep will hit it when the door is closed, causing the sweep’s soft vinyl edge to drop down snugly against the threshold.

Open the door to assure that the vinyl edge lifts sufficiently to clear the carpet or other flooring material as the door swings fully open. Adjust the sweep’s height on the door if necessary.

Next comes the “jamb-set” weatherstripping.

Jamb-set weatherstripping is an aluminum strip with a vinyl bead on one edge. It is nailed to the jamb around the perimeter of the door so that the door presses slightly against the bead when closed, forming a seal.

The weatherstripping is available in the same colors that the automatic door sweeps come in (for easy matching), and is found at most large hardware stores and home centers.

Installing this product requires an initial measurement from the top of the automatic door sweep at the bottom of the door to the top of the vertical door stop molding on either side of the door. Keep the door closed for this.

Cut one of the two long strips of weatherstripping with a hacksaw to the exact dimension. Keep the door closed and hold the strip against the vertical door stop molding so the vinyl bead slightly contacts the face of the door.

Nail the strip to the door stop molding with the nails provided.

Repeat this procedure for the other side of the door and for the shorter strip across the top portion of the door frame.

When complete, the vinyl edge should contact the door face at every point around the perimeter of the door when the door is shut.

Step inside and look carefully into the edges around the door. No spots of daylight should be visible. Adjust the strip as needed by tapping it toward the door lightly as needed with a hammer.

Finally, test the operation of the door locks. If the stripping is set too tightly against the door, the locks might not engage properly. Adjust as necessary by tapping the stripping away from the door slightly.

Incidentally, the Southern California Gas Co. offers a free door and window weatherstripping program for fixed- and low-income renters and homeowners. Contact the Direct Assistance Program hot line at (800) 228-4284.