Abandoned House with Broken Window
© Marina P. / Adobe Stock

New windows should make your home more comfortable, but if they aren’t installed correctly, they’ll do just the opposite. Poorly installed windows can leave you with chilly drafts, damaging leaks, and high energy bills.

Spot the signs early, though, and you can get a bad installation job corrected before it causes any major problems.

Strange Noises

Squeaking, creaking or cracking noises when you open or close the window are often the first signs of a bad installation. These sounds usually mean the window is too tight or loose, or that the hinges, stays or other hardware were installed incorrectly.

They can also come from windows with low quality glass and frames, which deform more with temperature changes, and can become too loose or tight depending on the weather.

Noticeable Gaps

A fairly obvious sign of trouble, gaps between the frame and the window sill or wall mean the window wasn’t the correct size to begin with. Either the installer chose the wrong size of prefabricated windows or didn’t measure properly for custom windows.

Gaps like this can cause air leaks that waste your heated or cooled indoor air and water leaks that damage your walls and floors. Smaller gaps can be corrected with shims, backer rod and caulk or expanding foam, but fixing large ones might require replacing the window entirely.

Difficulty Opening and Closing

This problem usually shows up in double-hung sash windows, but it can happen with slider, casement, and awning windows, too. If a window was correctly installed, it should open and close fully and smoothly without any sticking.

If your window sticks so much you have to force it to move or it doesn’t reach the frame when you try to close it, you have a problem. Either the sash wasn’t properly aligned, or it’s the wrong size for the window. A window like this is liable to have gaps that will eventually cause leaks.


If you’ve noticed the room where your new windows were installed suddenly feels drafty, the windows are probably to blame. Even gaps that are too small to see can still let chilly drafts into your home, along with excess humidity and outdoor air pollution.

This usually happens because the windows either weren’t fit or weren’t caulked properly. Incorrect installation can also cause the seal on a double- or triple-pane window to break, which can leave you with drafts.

You might be able to pinpoint the gaps just by holding your hand up to the window frame and feeling for air movement. If not, use a lit incense stick or HVAC smoke pen. Air coming through any gaps will blow the smoke around.

Smaller leaks around the frame might only need caulking, but if the seal on your double- or triple-pane window is broken, you’ll need a new window.

Water Damage

A badly installed window is highly likely to leak. At first, you might only notice slight dampness or mold under the window or along the window frame and sill. Over time, though, you’ll find peeling paint or wallpaper, puffy walls, large patches of mold growth, and eventually, rotting walls.

Leaks due to bad installation typically happen because the windows aren’t level. Other times, it’s a case of flashing that was poorly installed or broken. Using building paper in place of window flashing can also lead to leaks.

Because a leaky window can cause serious damage to your walls and floor, contact your installer as soon as you notice any signs of water infiltration.

Fog Between the Panes

Between the panes of a double-pane window is a layer of inert argon gas that slows down heat conduction and improves your window’s energy efficiency. If the window’s seal breaks, this gas escapes and water vapor can seep in. The water vapor condenses into fog or water droplets between the panes of glass.

If you see this, your window is permanently damaged, and you’ll need a replacement. If it’s a new window, damage during installation is the most likely cause. As long as the window is still under warranty, replacement shouldn’t cost you anything.

Bad Caulking

More than just a finishing touch, caulk plays an essential role in your window’s ability to keep out the elements. Your windows should have a visible, clean line of caulk around them. Caulk that’s uneven, patchy or generally sloppy suggests your installer might have been equally lazy with the rest of the job.

The exception is caulk on stucco, brick or textured siding, which can develop minor gaps as it dries no matter how carefully your installer applied it. Caulk takes several weeks to cure fully, so check it again a month after your windows have been installed.

Leftover Mess

Even the most skilled window installation job can make quite a mess. That’s why installers generally advise you to move furniture out of the way or cover it and cover the floor.

No matter how much mess they make, though, reliable installers take the time to clean up thoroughly by removing debris and sweeping up dust. An installer who skips cleanup is likely to have skipped steps during the installation, too.

Also, pay attention to the window glass. Window installers use a variety of adhesives, fillers, caulk, and other sticky stuff that can end up on the glass. Most installers will clean the glass, but there’s always a chance they’ll miss spots.

Check your windows after installation and let your installer know about any spots so they can clean immediately to prevent staining.

A few small smudges or streaks are no problem, but if your installer left your window a mess or left any permanent stains, it calls the rest of their work into question.

No Warranty

Your new windows should come with a manufacturer’s warranty. If you didn’t get a warranty, it’s a red flag that your windows weren’t installed correctly. Every window manufacturer provides specific installation guidelines that must be met in order for the warranty to be valid.

If your installer didn’t give you the warranty, it suggests they made mistakes or cut corners in a way that voided the warranty.

By inspecting your newly installed windows and looking out for signs of trouble, you can protect your home from a lot of potential damage. If you suspect you’ve got a case of poorly installed windows on your hands, contact your installation company. They should be able to correct any problems at no extra charge.

Editorial Contributors
Henry Parker

Henry Parker

Henry Parker is a home improvement enthusiast who loves to share his passion and expertise with others. He writes on a variety of topics, such as painting, flooring, windows, and lawn care, to help homeowners make informed decisions and achieve their desired results. Henry strives to write high quality guides and reviews that are easy to understand and practical to follow. Whether you are looking for the best electric riding lawn mower, the easiest way to remove paint from flooring, or the signs of a bad tile job, Henry has you covered with his insightful and honest articles. Henry lives in Florida with his wife and two kids, and enjoys spending his free time on DIY projects around the house. You can find some of his work on Today’s Homeowner, where he is a regular contributor.

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