Window Caulking: Seal Windows for Winter in 3 Steps

Updated: Jan. 23, 2024

Here's how to seal windows for winter in order to save money and heat when the temperature drops.

Caulking windows is one of the most cost-effective ways to reduce your heating bills. But how do you know where to start? Here are the top three things you should do to seal your windows for winter.

Locate the Leaks

Figure out where the biggest window leaks are so you can concentrate your time and money on fixing the worst problems. The best way to do this is by having an energy audit, including a blower-door test, done on your house.

The home energy audit will include recommendations for how to seal windows for winter. Drafty windows let in the cold air, and that can make your favorite corner or even your entire house uncomfortably chilly. Learn to winterize your windows to stay warm this winter.

But, if you can’t afford an energy audit, there are also DIY methods for finding air leaks and drafts. Simply going from room to room on a cold, windy day and feeling for drafts around your windows is effective. Draw a simple floor plan and make note of which windows seem draftiest. Then you can fix these first.

Another method is to use a stick of incense as an indicator of drafts. Or you can buy a temperature sensor and use it to check around the windows for cold spots.

Do the Easy Fixes First

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Caulking around windows is easy and cheap and should be the first line of defense against winter drafts. Caulk around the exterior perimeter of leaky windows. Also, seal the crack between the interior trim and the wall with caulk, as this is where air leaking around the window frame will most likely enter the house. You can even temporarily seal the entire window with removable caulk if you don’t intend to operate the window in the winter.

Need an easier fix to seal your windows? Covering your windows with heat-shrink film is another cheap and easy fix that will help seal and winterize your windows.

Invest in Long-Term Solutions

You’ll recover the cost of caulk or heat-shrink plastic window film rather quickly with reduced heating bills. But, you should also consider long-term solutions as time and money allow. Of course, simply replacing your windows with more efficient ones is one option. But, it would likely be decades before you would recover the cost of this fix. Before you go to this extreme, consider these options:

  • Add storm windows. Studies have shown that adding storm windows is a very cost-effective way to reduce energy bills and winterize your home. Unfortunately, you can’t add storm windows to casement or awning-style windows.
  • Insulate and seal around your windows. In most houses there is a space between the wall framing and window frame. Traditionally, if this space was filled at all, it was loosely stuffed with fiberglass batt insulation. And, while this provided some insulation, it didn’t provide a good air barrier. Today, it’s common to fill this space with spray-foam insulation, but if you live in an older house you probably don’t have this improvement. To find out if you do, remove the trim from one of your windows and look. Removing the loose-fill insulation and filling this space with spray-foam is a great way to help seal your windows for winter. And, while this is a labor-intensive job, it isn’t terribly expensive.
  • Add interior insulating window coverings. Covering the interior of your windows has several energy saving advantages. First, simply covering the glass at night reduces radiant heat loss. And if you install thermal drapes or window coverings that include a seal around the perimeter, drafts and heat loss through air movement will be reduced as well. Window Quilts are a good example of a window covering that seals and insulates from the inside. A search of “insulating curtains and blinds” will provide more choices. Even inexpensive, pull-down blinds reduce window heat loss enough to be a good investment.