You needed new windows so you hired a contractor and had them put in replacements. Your last check is long since cashed, but now you’re starting to notice something odd: your windows are letting in cold air. And on closer inspection, there are some traces of mold just beginning to grow on the sills. You have the sinking feeling that they weren’t properly installed. But how do you know for sure?

There are usually some telltale signs that your installer didn’t know what he was doing—even if he didn’t visibly scratch his head while the windows were going in. Here are some ways to diagnose improperly installed windows—and what to do about it after the fact.

Woman Female WIndow Repair Contractor

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Signs That Your Windows Aren’t Properly Installed

  • There Are Visible Gaps Between the Window Frame and the Sill or Between the Frame and the Wall. Your installer should have carefully measured the window before installing, and the measurements should have been taken from the inside of the home. There’s no excuse for windows that don’t fit right—it just means your installer made a mistake in their measurements. If your window is not one of the standard window sizes, your contractor should have a custom window built to sit flush against the wall, with no gaps in between.
  • It’s Noticeably Drafty or Stuffy, Or You Notice a Sharp Uptick in Your Energy Bills. One of your windows’ primary jobs is to keep you protected from the weather, so if you notice that your home is less comfortable than it used to be, or if you hear or feel wind whistling through the window, that’s a pretty bad sign. Ditto if your energy bills suddenly spike. Leaks can significantly impact your home’s energy efficiency, so you want windows that keep the weather out—and your heating and cooling in.
  • You See Leaks or Signs of Water Damage. Another common consequence of poor installation is leaky windows—and the inevitable water damage that comes with them. Common signs of water damage are peeling paint, sagging or puffy walls, rotting wood, and powdery black spots (i.e. mold) along the frame, sill, and adjacent walls. If you see this, you know you need to get it fixed fast (have you ever done the numbers on mold remediation?), so call a contractor ASAP.
  • You Notice Condensation Between the Window Panes. Condensation between the window panes is one of the most obvious indicators that your window was improperly installed. It’s also a sign that moisture is getting inside the window. Usually, you’ll notice other issues along with this, such as drafts or rising energy costs. Either way, you should probably have a pro out to look at your windows.
  • The Sashes Are Hard to Open. This is a pretty common installation mistake. Homes do settle over time, but when you first have your windows installed, they should operate smoothly—meaning they’re easy to open, with no creaking or sticking on the way up. If not, it’s a sign that the contractor installed a sash that is slightly smaller or bigger than the rest of the window. This can lead to leaks, air infiltration, and mildew in the long run.
  • There’s No Warranty with the Windows. Any new windows that go into your walls should come with a manufacturer’s warranty—otherwise, it could mean that they weren’t professionally installed. In fact, many dealers take pains to make sure that their windows are installed according to manufacturers’ guidelines, since it could void the warranty otherwise.

How to Fix Improperly Installed Windows

You can try reaching out to the original installer and asking them to fix the problem. If they’re worth their snuff, they’ll want a chance to correct the issue, so they may rush right out and get you squared away. After all, their reputation is on the line!

However, the best solution may be to hire another contractor and have them remove the windows and reinstall them correctly. Of course, that won’t help you if your first installer used windows that were too small in the first place. Depending on where you got them, the seller may allow you to return the windows or exchange them for the right size, especially if they are a standard size and not a special order.

Still, you’ll want the help of a contractor—preferably someone who knows what they’re doing this time. Read on for some pointers on picking out a reliable window installer.

Dog and grey cat on the window

Tips for Hiring a Knowledgeable Windows Contractor

In a perfect world, every contractor would do their job right the first time, but that’s sadly just not the way of things. Be sure to properly vet your next window installer so that you don’t end up right back here in a few weeks. Here’s how to tell if they know their stuff:

  • Look for an Installer Who Has Experience with Your Windows. Different replacement contractors specialize in different materials and areas of expertise. For instance, one dealer or installer may primarily sell vinyl frames, while another deals exclusively in wood. One may focus on energy-efficiency, another on economy selections. Check out your contractor’s website ahead of time (if they don’t have one, that’s a bad sign!) to get a feel for their areas of expertise.
  • Get Several Bids Before You Settle on an Installer. If you’ve been burned by an installer before, you’re probably feeling (understandably) a little gun-shy about hiring the next pro. In fact, it’s better to collect between three to five bids before you make up your mind. That way, you can make sure you’re getting a fair price and picking the best pro for your money.
  • Read the Reviews. Sites like Yelp, Google Reviews, and Angie’s List exist for a reason. There, homeowners can speak their minds freely, so be sure to peruse these sites for reviews of the contractor you want to hire.
  • Review the Fine Print. Your contract should include some kind of warranty—both for the windows and a guarantee for the labor. A good manufacturers’ warranty extends for 10 years past the installation date. And most installers will guarantee their workmanship for at least two years. The absence of these kinds of niceties are a tip-off that your contractor isn’t really a pro. And that means they have no business messing with your windows!