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Most Common Ways to Window Seal


window seal

Insulated windows are not the only way to improve your energy bill. You can combat air leaks by using a window seal. Sealing a window has several benefits, and it is especially important to seal any leaks to help prevent damage to your HVAC system. Not only will you be able to save money on your energy bill, you will also save money in the long-term by protecting your HVAC unit.

 Air leaks are found when outside air enters the house through cracks and openings. Air takes the path of least resistance, so seal largest openings first. What are the easiest and most common ways to seal your windows?


Caulk is a budget-friendly way to seal your windows and is best used for the immovable parts of the window.  It is usually made of latex or silicone and comes in disposable cartridges. One cartridge will usually completely seal two windows.

Although the caulk gun is the most common way to apply caulk, caulking compounds can also be found in aerosol cans, squeeze tubes or ropes. These are typically used for smaller jobs because the caulk doesn’t store well for more than a few years.

When applying caulk, remove all old paint and caulk with a large screwdriver or putty knife. Clean the surface and let it dry completely. Once the area is dry, hold the caulk tube at a 45-degree angle to apply and apply the caulk in one continuous stream. It’s a good idea to practice applying the caulk on a newspaper to get the feel of it before applying it in a more conspicuous area. After applying the caulk for 2-3 feet, glide a dampened finger over the bead of caulk to smooth it out and push it deeper into the crack. Take care of any problems right away because wet caulk is easier to deal with than dry caulk.

Weather Stripping Single or Double-Hung Windows

Weather stripping is good for the movable components of the window. There are a variety of depths and widths so make sure you get the proper one for your job. You want weatherstripping to be able to withstand friction, weather, changing temperatures, and everyday wear and tear. Measure the perimeter of all windows to be weather-stripped and add at least 10% to accommodate for waste.

You will need both self-adhesive foam insulation and V-channel weatherstripping to seal single or double-hung (sash) windows. The first step is to clean the bottom of the sash, then let it completely dry. (The sash is the moveable part of the window made of the vertical and horizontal frame that holds the glass.) Cut the foam weather stripping to length and press the adhesive side against the bottom of the sash to form a tight bond.

Next, you want to clean the jamb, which is the main vertical parts forming the sides of the window frame. Once it is completely dry, cut 2 pieces of V-channel weatherstripping 1 inch longer than each sash height. Peel the backing and work it between the sash and jamb. Press firmly into the jamb and secure with finish nails into the jamb through the weatherstripping. Test it to make sure nothing catches on the nails.

Finally, clean the back of the bottom of the sash and allow it to dry completely. Cut a V-channel weatherstripping to match the width of the sash. With the sash raised a few inches, peel the backing and press firmly onto the back of the sash. The V opening should be up so it compresses when the window is closed.

Weather Stripping Casement Windows

Casement windows are windows that are hinged at the side. They operate by using a lever or a crank to open the window inward or outward from the room.

To seal casement windows, you will just need self-adhesive foam. Open the window and clean the outside of the window stop moulding. Let it dry completely then cut the foam to fit the top, bottom, and sides of the stop moulding. Remove the backing from each piece and press to the stop moulding firmly.

Storm Windows

A storm window is a window fixed to the outside or inside of a normal window for extra protection or insulation. Exterior storm windows fit most standard double hung windows and are the most common used. For outward swinging casement windows, you will need to use interior storm windows.

Before installing storm windows, make sure to take care of all rotted wood, missing or broken glass, and water leaks. All surfaces must be dry. Measure the width between the inside edge of the bottom, top, and middle of the window. Round down to the nearest ⅛ inch, if needed. Then measure the height from the top of the casing to the sill at its highest point.

Check for proper fit of the storm window by centering the storm window in the opening. Make sure all screw holes land on solid wood. Caulk the top and sides of the existing window, but not the bottom sill. Reposition the storm window and make sure the top is pushed up snugly into the very top of the opening. Secure the top corners of the window with screws.

Typical storm windows will come with a sill expander. Use your putty knife to tap down the expander tight against the window sill. The expander should have even contact along the bottom sill. Square up the storm window and install the rest of the screws.

With storm windows, there is a risk of condensation forming between the existing window and the storm window. To minimize this risk, ensure that the original window is airtight by caulking the top and sides before installing the storm window.

Which Window Seal is Best for You?

There are several quick and easy ways to seal a window. Use one or a combination of them to save money on your utility bill.  In some cases, your best option will be to do away with the old and take in the new. Replacing old, rotted, out of commission windows is a job for a professional, but you can use this opportunity to upgrade the framing materials and the coating on your new set of windows for more longevity and better insulation. Contact us today for a free energy audit to find out if you have air leaks. 







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