Sealing Winter Drafts from Windows and Doors

When the first real cold snap hits Calgary, you start to notice the small ways winter tries to get inside. It might be a little whisper of cold air on your neck when you sit in your favourite chair, or a floor that feels icy near the patio door. These drafts are more than just a minor annoyance. They represent heat loss, and that means your furnace is working harder than it needs to. Taking an afternoon to track down and seal these air leaks is practical seasonal work for a homeowner. It makes the house more comfortable and trims energy use at the same time.

Finding the Source of the Drafts

Before you can fix a draft, you have to find it. You do not need any special equipment for this. The simplest method is to wait for a cold, windy day and use your own senses. Slowly move the back of your hand around the edges of your window frames and door frames. You will feel the temperature change where cold air is pushing through. Pay attention to the corners, the spots where moving parts meet the frame, and any electrical outlets on exterior walls.

If you want to be a bit more methodical, you can use a stick of incense. On a calm day, close all the windows and doors and turn off your furnace and any fans to still the air in the house. Light the incense stick and hold it near the suspected leak points. If there is a draft, you will see the smoke trail get pulled into the house or pushed away from the wall. This works well for pinpointing even small air leaks that are hard to feel.

Simple Fixes for Doors

Exterior doors are common sources of drafts. The constant opening and closing wears out the seals over time. The two main areas to check are the weatherstripping around the sides and top of the door, and the sweep or threshold at the bottom.

Weatherstripping comes in several forms. The most common are self-adhesive foam tape and V-strip, or tension seal. Foam tape is easy to apply but tends to compress and break down after a few winters. V-strip is a plastic or metal strip that folds into a V-shape and springs open to fill the gap. It lasts longer but needs a bit more care to install. To replace old weatherstripping, pull it off, clean the surface of the door jamb thoroughly with an appropriate cleaner, and apply the new material according to the package directions.

For the bottom of the door, look at the gap between the door and the threshold. If you can see daylight, you are losing a lot of heat. Some thresholds are adjustable and can be raised by turning a few screws. If yours is not adjustable, or if the gap is too large, you can add a door sweep. These are strips of metal or plastic with a rubber or brush seal that you screw onto the bottom of the door. They create a tighter barrier against drafts.

Sealing Windows for the Winter

Windows bring a similar set of challenges. Like doors, they have moving parts that can create gaps. For operable windows, like casement or sliding windows, weatherstripping is the first line of defence. The same foam or V-strip products used for doors can work here. Make sure the window locks are properly engaged, as this helps compress the seals and create a tighter fit.

Another option for windows is temporary window insulation film. This is a thin plastic sheet that you apply to the inside of the window frame with double-sided tape. You then use a hair dryer to shrink the film until it is taut and clear. It creates a pocket of still air between the film and the glass, which acts as an extra layer of insulation. I have seen this make a noticeable difference in older homes with single-pane windows. It is an inexpensive way to get through the winter, though you do have to remove it in the spring.

I once inspected a character home in the Beltline where the original wood windows were beautiful but very drafty. The owner had carefully applied insulation film to every one. The difference in the feel of the rooms was immediate. It cut the drafts and also reduced the chill that you can feel radiating off cold glass.

When Simple Fixes Are Not Enough

Sometimes, weatherstripping and plastic film are just bandages on a bigger problem. If a window is foggy or has moisture trapped between the panes, it means the seal on the insulated glass unit has failed and it has lost its insulating gas. At that point, the glass unit needs to be replaced. If the door itself is warped or the window frame is rotten or cracked, no amount of foam tape will solve the problem. These situations usually call for replacement by a professional.

Drafts can also come from less obvious places, like cold air seeping in at the top of the foundation and getting into the floor system. Properly insulating and air sealing a basement can have a large effect on the comfort of the entire house. You can see what that kind of project involves on a Calgary contractor. When you are looking to hire a trade for larger jobs like window replacement or major insulation work, it is a good practice to check their reputation. The Better Business Bureau listing for Calgary is one place to start your reading.

A Note on Air Exchange

As you work to seal up your home, remember that a house needs to breathe. In the past, houses were drafty enough that fresh air was never a concern. Modern, tightly sealed homes need mechanical ventilation to exchange stale, moist indoor air with fresh outdoor air. Without it, humidity can build up, leading to other problems. A tightly sealed home needs a working system of fans and vents, like an HRV, or you might trade your drafts for issues like poor air quality and find yourself reading about window condensation. So, seal the unintentional leaks, but make sure your home's ventilation systems are clean and operating as they should.