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Seal windows and reduce heating costs – How to isolate drafts and keep your home warm in winter

To prepare for the colder season, you can take simple steps to seal your windows by repairing drafty spots. This is an inexpensive way to protect your living spaces from drafts and maximize heat during low temperatures. In addition, properly sealing windows can prevent moisture and mold growth, as well as air leaks during extreme weather conditions. Insulating window panes and trim requires a little skill and expertise, but they shouldn’t deter you. Here are some tips and basic sealing techniques you can do yourself at home.

Why you should caulk and winterize your windows

use cartridge gun with silicone sealant and seal inside windows before winter season

Insulating your windows for winter doesn’t have to mean costly replacement or extra work. Drafts at your windows can quickly cool your home in the winter as heat flows outside. This causes your heating system to work extra hard to even out the temperature, which can increase energy costs. In addition, air gaps not only let the cold in, but also allow heat to escape, which also leads to unnecessarily high heating costs. Whether you want to seal old windows or have newer ones that are a bit worn, simple solutions can keep them warm and cozy in no time.

seal large windows and prepare for the winter months with aluminum window frames

Up to 40 percent of heat loss can be attributed to open, unsealed windows with single glazing. When you waste energy this way, you increase your household’s CO₂ footprint and compromise both the comfort and air quality of your indoor environment. Accordingly, a window that leaks air can mean excessive energy loss and higher heating costs. Whether this happens in summer or winter, you shouldn’t lose air from your home or apartment, especially if you’re spending your hard-earned money to keep it warm or cool. There are several silicone sealants you can use indoors. If you need to seal your windows on the exterior, you should look for a sealant that provides a durable but flexible perimeter seal for exterior window and door frames.

Before you start caulking

prevent drafts in apartments and seal windows with sealing tape before the colder seasons

The best way to test your windows for leaks is to burn a stick of incense near all joints and connections. If the smoke flickers, you have an air leak. Also, check where one section of the window meets another, where the windows meet the frame, and where the frame meets the wall. In fact, water leaks from a window often result from a breakdown in the connection between the window frame and the wall. To prevent leaks, caulk the window where it meets the exterior siding. If the window pane is surrounded by wood siding, you can use a high-quality polyurethane caulk to seal any gaps between the window siding.

prevent cold air through the windows with the right sealant in bad weather conditions


There are a few drawbacks that you should consider before applying sealing tape to all your windows. For example, this is not a good option for windows that you want to open on mild days to let in some fresh air, as you would need to apply new tape. When you remove the tape, it can also strip some of the paint around your windows. Beyond that, sealing tape isn’t particularly effective, though you may not even feel the difference. However, if you’re looking for a quick and inexpensive solution, at least until you have the time to use a better method, sealing tape can help. This is especially true if you combine this option with other drafty window solutions.

If you want to use a sealing tape to seal your windows.

easy and short term solution to insulate windows with sealing tape to prevent mold growth

One of the easiest ways to seal some leaks is to apply a special window sealing tape, which you can buy at your local hardware store, over the edges of your window. Measure the perimeter of each window first, then add 10% to account for the material. You can choose vinyl, felt or metal caulking materials. However, these vary greatly in price and performance, so it’s best to do your research before making a decision. This will ensure you get the right one for your home. Also, clean your windows before applying the weatherstripping and make sure they are dry. When doing this, the outside temperature should be at least -7 °C. Apply sealing strips tightly to both the sash and the frame. Be careful not to let it interfere with the mechanism of the window.

avoid dampness on windows and prevent mold growth with proper sealant


You can seal some gaps on the sides, tops and bottoms of your windows to reduce drafts and stop heat loss. There are several types of weather stripping. You can use vinyl, aluminum or stainless steel V-channel on the sides of your double hung or sliding windows. The downside is that once installed, this material can make it difficult to open and close your windows. Felt seals create less resistance when you operate your windows. However, keep in mind that these won’t last more than a season or two. Also, don’t use felt where there is a lot of moisture, as it is more prone to mold growth. Highly visible, it’s also not the most attractive solution for sealing windows.

If you want to use sealant

keep your home warm and reduce energy costs by insulating windows with sealing compound

First, clean your windows and make sure they are dry. You can apply silicone sealant to all the joints in a window frame and the joint between the frame and your wall. However, when doing so, make sure you hold the cartridge gun at a constant 45-degree angle to get deep into the cracks. Caulk in a continuous stream as best you can, and if it seeps out of the crack, use a putty knife to push the caulk back in. Also, be careful not to skimp on the amount. If the sealant shrinks into the crack, reapply it to make sure a smooth bead forms to completely seal your cracks.

fill leaks and air leakage with silicone and seal windows to reduce heating costs in winter

If the existing sealant has cured and is coming loose, it is certainly a futile exercise to run sealant over it. The old sealant will continue to loosen and take the new sealant with it. Before that happens, you’ll be faced with a thick, messy sealant line that will mar the appearance of the window. Scrape off the old sealant with a steel putty knife. You can also make your own draft stoppers or shrink wrap kits. A lot of materials are needed – both in terms of the number of tools and the amount of each material – including fabric, scissors, tape, insulation, shrink wrap, pins, and most likely a sewing machine. For a DIY draft stopper, you’ll need to measure your windows, cut your fabric, fold it in half, sew seams, turn the fabric tube inside out, add insulation and sew it together.

How to seal your windows using a simple method.

apply polyurethane spray foam to joints between wall and windows and seal windows

If you are willing to remove either your exterior or interior window trim, you can seal window and door leaks much better and permanently. Using spray foam not only prevents air from getting in, but also makes the treated area waterproof. Here’s how:

  • Use a crowbar and hammer to remove the window trim (either inside or outside – not both).
  • Fill the cavity with expanding spray foam in a can.
  • Don’t worry about overfilling. Allow it to protrude from the wall. What you should not do is touch the foam while it is wet. You will make a huge, hard-to-clean mess.
  • After the foam dries (it takes several hours), cut off the excess with a knife.
  • Replace the trim in the reverse order you removed it, touching up the paint as needed.
  • Leaks also occur when weatherstrips are worn. You may need to remove the operable portion of the window to find the weatherstrip:
  • For sliding windows, open them halfway and lift the window out of the bottom track. Then pull the window out of the opening at the bottom first.
  • For single-hung windows, usually just loosen a lever on the side rail(s) of the window frame. Contact the manufacturer for specific instructions.

insulate wooden windows with the right sealing tape and prevent drafts from entering in winter

After you remove the operable portion of the window, it will be fairly obvious where the weatherstrip is located and how to replace it. Most hardware stores offer replacement weatherstripping in peel-off rolls. If you’re not sure what to do, take the section you removed to the store or take a picture of the area that needs your attention. You may need a solvent to loosen old sealant. Adhesive solvents are available in spray cans for easy application.

Alternative window sealant

craftsmen use sealing tape on window frames for insulation

Another trick is to make an interior window seal using plastic wrap, cling wrap or bubble wrap. One of the most popular DIY window sealing methods for winter is to apply plastic such as cling film or a special plastic window sealing film from a home insulation kit to your glass with double-sided tape. Then use your hair dryer to shrink the plastic over the window. For bubble wrap, you can spray a mist of water on the glass and then apply the film. The water will act as an adhesive.

seal the outside of the windows with silicone sealant against leaks and drafts

However, using plastic is not the best way to seal windows for the winter, as the cracks around your windows will still remain open to heat loss. Plus, plastic doesn’t exactly create a strong barrier for insulating drafty windows. It also doesn’t do the aesthetics of your home any favors. But as with other caulking methods, it can help a little until you decide on a more permanent and high-performing method. Add insulating window coverings for the interior as well. Covering the inside of your windows has several energy-saving benefits. First, simply covering the glass at night reduces radiant heat loss. If you add window coverings with a perimeter seal, drafts and heat loss from air movement will also be reduced.