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How to Keep Cold Air From Coming Through Your Windows

Conditioned air that is allowed to escape through and around windows can be both uncomfortable and expensive due to the drafts they allow. Windows and doors are usually responsible for the majority of the air exchange inside a home, so it is important to control it. Today we will discuss how to keep cold air from coming through and around your windows.

How to Keep Cold Air From Coming Through Your Windows

Why Is Air Coming In Through My Windows?

Windows are notorious for leaking conditioned air out and letting outside air into a home. Both windows and doors are mechanical and have moving parts, so they must be well maintained or eventually, they will fail to perform. In many instances, the window is either worn out, improperly installed, or broken.

Windows Leaking Air Through the Rough Opening

Another common culprit of leaky windows is a failure of not the windows itself, but the opening it sits in. For example, vinyl windows are a staple of modern construction because they are cost- effective and do a great job. However, windows are only as good as the installation, so perfectly functioning windows can still leak air due to a faulty installation. 

Improper Installation Causes Premature Wear

In most cases of improper installation, the window was installed out of square or plumb or the caulk used to seal the window has failed. Mechanical failures are often the result of windows installed out of square or plumb, because it causes unnecessary friction. The unnecessary wear caused by the friction shortens the life of the window, often leading to replacement.

Low-Quality or Incorrect Sealant Can Cause Air Leaks

Perhaps the most common reason for leaking windows is the use of unapproved sealants to seal the window against the frame. A common mistake occurs when a rookie installer accidentally uses indoor or kitchen and bath caulk to seal a window. Ultraviolet radiation can break down these sealants, causing them to detach from the surface and create an opening.

The Windows Are Old and Worn Out

Windows have a lifespan, although we tend to consider them permanent unless they are damaged. Windows have several important components, but none more so than the glass (also called the glazing) and the seals around them. If either fails during normal operation, they can leak conditioned air as though they were partially open. 

9 Useful Options to Stop Air From Coming Through Your Windows

1. Re-Caulk Around the Window

If air is leaking in and around your windows, the cause is likely that the caulk or sealant used to seal the gap between the window frame and the rough opening has failed. Windows must be sealed with caulk designed for doors and windows, including UC protection. The installer must use an appropriate caulk when the window is installed or the caulk will eventually detach. 

Exterior surfaces, including windows and doors, must be sealed with high quality, exterior grade, UV resistant caulk. Never use kitchen and bath caulk outdoors, even if it is 100% silicone because it will degrade in sunlight. Always use a high quality sealant around windows, ideally one that works in any weather, eliminates joint tape, and bonds to wet surfaces like this one.

2. Add Interior Storm Windows or Inserts

A more elaborate option may involve the installation of storm windows or window inserts to your existing windows. Historic homes, for example, are great candidates for these products as they essentially encase the window sash, protecting it from the inside. Exterior storm windows are also very effective, but are often ignored in favor of the more attractive interior version.

Both storm windows and window inserts are popular DIY projects, as they are often sold in kit form. A do-it-yourselfer with a well-stocked tool box should have little trouble installing either of them. No two are exactly the same, so even the pros will use the directions that come with each kit and follow them closely.

3. Check and Reset the Window’s Operation

Sashes that are not properly aligned will create a space, allowing air to escape. If you are handy with carpentry tools, sometimes you can reset your own windows in the event your sashes are incorrectly aligned. Unfortunately, this trick will usually work best with replacement vinyl windows, but it may work with older wooden windows as well. 

Resetting the window involves detaching it from the rough opening. You can access the mounting screws (one in each corner) by popping off the screw cover with a putty knife. If you remove three of the four, the window should pivot around the remaining screw and move in all four directions without falling out. 

Now you can use a square and level to correct the window’s position and return the screws. Be careful not to overtighten the screws as they could break the window frame. Note you may have to drill new pilot holes if your windows were severely out of plumb.

4. Install Window Film

Window film is a quick, inexpensive way to stop a draft by covering the area with a self-adhesive film. The film material is often sold in rolls and can be used to stop airflow around a gap, loose seal, or crack in the glazing. Window film should be considered temporary, however, and is often used sparingly if other options are available.

5. Install Weather Stripping

Some windows, like those out of square, will develop a space between the bottom of a closed sash and the window sill. Windows come with a seal in this location, but an out of square sash will not contact the entire window sill, leaving a gap for air to pass through. Often the best way to identify this problem is if light can be seen under a closed sash.

To correct his problem, some window manufacturers engineer small adjustment screws into the hinge of one, or both sashes. Not all window designs will be adjustable, but if yours are, the adjustment screw is often an allen screw, so you’ll need a set of wrenches. There may be two adjustment screws if your windows are casement versions.

To adjust the sash, you can refer to the instructions that came with the window, or just make small quarter turn adjustments and test. The pros will usually adjust one direction at a time to avoid making too many adjustments at once, making the problem worse. If your window is perfectly adjusted but still allowing light or air to pass through, you may need to replace the sashes.

6. Replace the Sashes


If the other options haven’t worked, you might be able to replace just the sashes instead of replacing the entire window. Many window manufacturers provide replacement sashes in the event damage repairs must be made. The easiest way to replace a faulty sash is to either call your local window repair company, or just order one yourself.

To order your own sash, you’ll need the serial number of your window. Most of the time, the label will be located either on the inside of the track of the window frame, or on the outer edge of the sash itself. If yours is there and readable, you can contact the manufacturer of the window and order a replacement.

Window labels are usually a sticker, which can fall off once the sash gets wet. If this happens, remove the sash by disengaging the hinge pin and lift the sash from the window frame. Measure the height and width of the sash, any information on the glass, and provide the information to your manufacturer. Most manufacturers can build a new custom sash in just a few weeks.

7. Reglaze Old Windows

If your windows are very old, you may have wooden windows with glazing putty holding the glass in. Glazing putty has the consistency of clay and hardens to form an effective watertight seal. Glazing is subject to deterioration over time however, so it must routinely be replaced.

To reglaze a section of glass, just use a putty knife and scrape away anything that is loose, being careful not to remove the push points. Push points are small metal tacks that penetrate the mulling strips between the panes, holding the glass in place. If any pop out, just take a pair of needle nosed pliers and push them back into a different location.

To use the glazing putty, most pros roll it into thin ropes about ¼” wide and apply it as needed on both sides of the glass where the mulling separates the panes. The pros often use a wet finger or shaping tool to smooth out a uniform, consistent bead. After the glazing putty has dried, they use a razor blade scraper to remove any squeeze out of the putty.

8. Weird Hacks

Occasionally, an odd hack can save you both time and money. Referring back to leaking glazing, you’ll remember that the putty or rubber seal holding in the glazing could be a culprit of an air leak. If the leak is very small around these areas, you can use household items like nail polish to repair it. Most good adhesives, like super glue and epoxy will also work.

Just apply a thin coat of clear nail polish over the gap or crack and allow it to dry. Go back over the same crack again, but this time apply the nail polish from a different angle to cover any remaining gaps. Usually a third coat will seal the crack, but you can add as much as needed. If required, the nail polish can always be removed with nail polish remover.

9. Insulate Around the Window

If you have an older home or one in need of repairs, it may be worthwhile to reinsulate around your windows. Energy conservation is more important now than it was in the past, so some older windows may have no insulation at all. If you can feel a draft around the window trim, but can’t see a leak, the insulation is probably absent.

To correct the problem, just remove the trim around the interior of the window (known as window casing) and expose the space between the rough opening and the window frame. The pros use loose fiberglass insulation to insulate these spaces, but avoid packing it too tightly. Expanding spray foam insulation is not recommended for small gaps, as it leaves little room for expansion.

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