Sealing air leaks around exterior doors is the hardest task. You need to install weatherstripping that stops air but allows you to continue to open and close the door. (Tim Carter)

You want to be comfortable in your home during frigid winter months and I’m sure you want to save money at the same time. Minimizing cold air infiltrating into your home will go a very long way to satisfy both goals. The first place to start is with the weatherstripping, or lack thereof, around your windows and doors.

Weatherstripping is a common product that’s available in all different shapes, types and made from different materials. You’ve probably never really paid much attention to it around your doors and windows, yet you rely on the same product to keep your food cold and frozen. The seal on your refrigerator and freezer door serves the exact same purpose of the weatherstripping around your home’s windows and doors -- it keeps the cold air in your refrigerator/freezer stopping it from entering your kitchen.

The old school

Windows and doors in older homes rarely had weatherstripping. Heating fuel was cheap. The steel casement windows in my childhood home had no weatherstripping and I used to help my mom install temporary rope caulk around the edge of the window to stop air leakage. As crazy as it sounds, you can still buy this sticky rope caulk but there are now better products that are not as messy.

What’s causing the air leak?

Some air leakage is just caused by an ill-fitting door or a window that’s not been locked. Modern windows of all types rely on the locking mechanism to pull the sash tight against the window frame and factory-installed weatherstripping.

Open the window first, inspect it to make sure the existing weatherstripping is not damaged. Check to ensure there’s no debris that’s collected on the weatherstripping. If all is well, close the window and lock it. See if you notice a vast improvement. At my home, it makes a huge difference when I lock the windows.

If you try this on a bitterly cold day, be aware that the simple cold-air convection currents that cause air to fall down across the glass to the floor can be mistaken for air infiltration. You may not have an air leak.

A stick of burning incense next to the edge of a window can be used with great care to help detect true air infiltration. Air pouring into the room through a seal failure will cause the incense smoke to stream into the room rather than float slowly up to the ceiling. Use extreme caution with a stick of burning incense around any flammable curtains or window shades.

Doors are hardest

Sealing air leaks around exterior doors is the hardest task. You need to install weatherstripping that stops air but allows you to continue to open and close the door. Simple aluminum strips that have a long tube of compressible rubber can be fitted so the rubber makes a tight seal against the door when it’s closed. You need to cut these products to fit the height and width of the door and use small screws to secure the aluminum to the door jamb.

If the air leakage is along the bottom of the door, check to see if your door has an adjustable threshold that’s not at the right height. These thresholds are centered under the door and have screws that allow the wood strip to go up and down until they contact the rubber weatherstripping under the door. You need to lay on your belly to make this adjustment.

If your door doesn’t have an adjustable threshold, there are aftermarket rubber weatherstrips that you attach to the inside bottom of the door. When the door is closed the rubber strip should be in contact with the floor or the door threshold to seal out cold air. These are not easy to install, so be sure to read any and all installation instructions.

Windows are easy

Most people don’t open windows in the winter. This means you can install a temporary self-adhesive foam strip around the edge of the window where the chilly air is leaking into your home. This solution may not make for a cover photo for a home magazine, but it will stop most of the cold air.

Some air leakage around windows may not be caused by faulty weatherstripping. It could be air leaking around the frame of the window and entering through tiny cracks on both sides of the trim lumber that surrounds your windows. Carefully applied latex caulk can stop this air leakage in its tracks.

Low-cost fix

If money is tight and you can’t afford the modern weatherstripping products, you can revert to inexpensive painters tape to stop almost all air leaks around windows. This tape may not look attractive, but if you apply it around all places where you feel air entering your home, it will stop the air. This tape is designed with a special adhesive that allows it to be removed in the spring without damaging your window or wall finishes.

Tim Carter, author of the Ask the Builder column, wrote this story for The Washington Post. He can be reached at