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Insulate windows before winter – How to keep your home warm with the right insulators.

If you have noticed drafts in your home during the colder winter months, you can insulate your windows and retain heat. Insulation of this kind can help you both reduce heating costs and provide more comfort in your living spaces. Rising energy prices and seemingly endless cold snaps mean that insulated windows are more important than ever right now. Here are some common materials and methods to help you find the best and most cost-effective ways to insulate your home.

Why you should insulate your windows

insulate windows with various insulating materials such as thermal curtains or roller blinds and window film or sealing tape

Although a window seat offers perfect views of snow-covered branches, it may not be the most comfortable place to sit on chilly winter days. During the cold season, a lot of heat can escape through the glass panes as well as through cracks or gaps around the window frame. In such cases, put on a blanket or at least a thick sweater before you risk catching a cold. In addition, the average house or apartment typically loses up to one-third of its stored heat energy for heating due to poor window insulation. Fortunately, there are several ways to minimize this heat loss. To do this, you can follow a few simple steps and spend a weekend preparing your windows for the low winter temperatures.

keep optimal temperature in the room during the winter season and insulate windows for more thermal energy

So before you look at large living areas like walls, ceilings and floors, consider smaller break-in points like windows, which are the more likely culprits. After all, insulating and air sealing them is key to keeping your home warm in colder weather and cooler in the summer. However, while some measures are relatively inexpensive to implement, others, such as exterior or interior wall insulation, can be more expensive. Replacing windows with more energy-efficient versions can also be a costly task. Therefore, finding ways to keep heat inside is essential, especially for those with older double glazing or single glazing.

Start with the outside of the window frames

apply silicone sealant on the outside of the window frame and insulate windows with it

Decades of exposure to weather conditions can weaken one of the most important defenses against heat loss – exterior seals. Once these begin to crumble, cracks can form around the window frame. So if you feel drafts coming from your closed windows, take quick action to replace the exterior insulation along the window frames before the weather worsens. Follow the next steps to get the job done easily:

  • First, check the weather before you start the process. For a successful sealant application, you need 24 hours of clear skies, and no snow or rain. The ideal temperature should be above about 7 °C.
  • Then use a strong spatula to remove the old caulk and peeling paint from the window edges.
  • After that, wipe the surface with a damp cloth to remove all residues.
  • Allow the surface to dry for a few hours so that the new caulk adheres well. It’s best to start the project early in the day to allow enough drying time. You can also let it dry overnight, but depending on the outside temperature, you may have a cold night after scraping off the old grout.
  • First, load a cartridge gun with exterior silicone sealant and hold it at a 45-degree angle to get deep into the cracks around the window frame.
  • Then apply a continuous bead of sealant between the frame and the trim around the window. Any sealant that oozes out of the crack should be carefully pushed in with a putty knife.
  • Allow the new sealant to cure overnight, thereby allowing the best protection from wind and moisture.

Choosing the right insulating materials for indoors

cheap option to insulate windows with sealing tape


The window sashes, or the parts of the window that move to open and close, are the main points most people focus on when insulating their windows. While insulation is important here as well, don’t neglect the window glass or other draft-preventing insulators. It’s best to take a three-pronged approach to insulating the inside of your windows by using sealing tape, sealant, window film, spray foam, draft stoppers or energy-efficient window decorations like thermal curtains.

enjoy the view from the window on a winter day with a warm cup of tea

In addition, understanding how and why an insulation product or material you want to use to insulate your windows can help. Therefore, be sure to familiarize yourself with the specifics of each insulating material before you begin the thermal insulation process.

Use sealing tape and insulate windows

apply sealing tape to the window frame and as a cheap variant insulate windows before winter


Sealing tape is an excellent, quick and inexpensive means of insulating windows indoors. One of the most common types of draught excluders, which cost little, are the self-adhesive foam strips that you can buy in rolls and cut to length. Do you have a gap where the window moves? Use sealing tape, either applying it where there is none or replacing an old one with it. After all, if the strips start to crumble, replacing them is one of the quickest ways to improve the insulation of your windows without having to replace them. Peel-off strips with self-adhesive backing are also still easy to remove by hand without tools. However, after removing the sealing tape, it is recommended to wipe the window sash with a damp cloth and household cleaner. Then let it dry thoroughly before applying new sealing tape to it. Here are the instructions for applying it:

insulate windows with sealing tape as a simple and inexpensive alternative to replacing the glazing

  • Unroll the sealing tape and start pressing it tightly around the window with your fingers. If you need to press the tape in a little more, you can use a blunt object like a paint stirrer.
  • A pointed object like a putty knife can cut the tape, but it also effectively allows the material to get into tight spaces.
  • Move slowly and methodically to make sure the weatherstrip fits snugly in the gap.

Thermal insulation with window film

reduce heating costs and apply window film before cold season

Applying window film is also a common method of insulating windows, as it is inexpensive to purchase and effective. The film is made of plastic and is often sold in kits that include everything you need to apply it, including tape. Here’s how to apply window film:

use a hair dryer and heat window film for thermal insulation

  • First, make sure your window is sparkling clean before measuring it and cutting the film to the size you want.
  • The manufacturer’s instructions usually indicate that you should leave a little room around the edges for sizing.
  • The tape is then applied around the frame so the film can adhere to it.
  • Once you’re sure there are no wrinkles or creases in the film, you’ll need to heat it to shrink it for a tight fit. This is usually done with a hair dryer.
  • In addition, a window film is usually easy to remove when you no longer need it. However, when doing so, keep in mind that the tape can sometimes take paint with it, especially on old wooden window frames.

thermal insulation of windows with bubble wrap can be energy efficient but compromise views

Another trick for thermal insulation of windows is to stick bubble wrap on them. This is a solution that not everyone would jump at, but an effective one nonetheless. In doing so, don’t expect to be able to enjoy the beautiful view when you open the curtains. Connoisseurs also suggest misting the windows with water before sticking the bubble wrap to the window with the bubble side facing the glass.

Use silicone sealant to insulate gaps and cracks on the window.

apply silicone sealant with a cartridge gun in gaps or cracks in the window frame

Silicone caulk is quite popular with do-it-yourselfers and offers a particularly effective way to insulate windows. Use silicone sealant to seal gaps between the window frame and the wall, as well as any gaps in and around the frame. Before you start, however, scrape off any peeling old paint or sealant, and then again use a cartridge gun to neatly apply new silicone sealant. However, don’t use it to clog the tiny round or rectangular outer drain holes that are there for the drain. You will probably need about 1/2 of a cartridge of sealant for a window. If you are new to caulking, practice the technique on a paper towel before you insulate your windows. It will help you develop the pulling motion you need to dispense the sealant into the crack as it comes out of the tube. Here’s how:

  • First, remove old and cracked caulk with a putty knife or screwdriver.
  • First, make sure the area is bone dry before caulking.
  • Then cut the tip of the caulk hose at a 45-degree angle.
  • Insert the hose into the sealant gun and pull the trigger to introduce the material into the crack.
  • Seal in one motion rather than with starts and stops. This will create a clean, continuous strip.
  • When the sealant appears to flow out of the crack, push it back in with a putty knife.
  • Allow the sealant to cure for 24 hours.

Apply spray foam to the openings.

handyman applies spray foam under window sill for thermal insulation

Older homes typically need more thermal insulation around interior windows. Expanding spray foam may be easier to use in such cases than hand-inserting fiberglass batting.

  • First, start by removing the trim around your window.
  • To do this, place a putty knife behind the molding to carefully pull it off and expose the large gaps around the frame.
  • Next, insert the nozzle of the spray foam can deep into the gap, (this will likely be a few inches deep) before spraying.
  • The foam will begin to expand immediately, but it may take hours to fully expand.
  • Once the foam is completely dry and expanded, replace the molding around the window.

Install horizontal draught excluders and insulate the windows.

insulate windows and store heat in the room with a purchased or homemade draught excluder

This is another easy and inexpensive way to stop annoying drafts and keep heat inside. Draught stoppers are small, long, tube-like cushions that sit on under a door or on the windowsill to block any gaps. You can usually find these pre-made at hardware or home improvement stores. However, you can also make your own draft stopper with long socks by filling them with fabric and sewing them. The snakes should be as long as your window.

  • Also fill the sock or fabric tube with rice, dried corn kernels for popcorn, or dried beans.
  • Close the end of the tube after filling by hand or machine stitching.
  • Close your window and place the draught excluder tightly over the place where the sill and the bottom of the window meet.
  • This seal can prevent cold or hot air from coming in or out through gaps and cracks.
  • If you have a double-hung window, you can also place a draft stopper on the top rail above the sash lock when the window is closed to prevent even more drafts.

Use thermal curtains or blinds for thermal insulation.

special thermal curtains prevent heat loss or overheating of living spaces and can insulate windows

Thermal curtains and blinds are one of the best ways to insulate windows. If you buy high-quality products to go with them, they should also be able to prevent your living spaces from overheating during the summer months. Basically, thermal curtains consist of at least three layers of material that work together to regulate the temperature of a room. It is also possible to buy thermal blinds. These usually have tiny honeycomb pockets or the like that trap cold or warm air to create a cozy and energy-efficient atmosphere.

  • It makes a difference how you hang such curtains when it comes to energy efficient window decorations.
  • Thermal curtains should be hung as close to the window as possible and extend to the windowsill or floor.
  • Attach the curtains as far as possible from the ceiling for maximum effectiveness.
  • Seal the curtains on both sides to further minimize heat transfer.
  • Using magnetic or loop tape to seal the sides of the curtains to the wall and overlapping panels in the center on the sides can reduce heat loss by up to 25 percent.
  • When such blackout blinds fit tightly against the window, they too can reduce heat loss through windows by 40 percent or more and reduce unwanted solar heat by up to 80 percent.