Your house may not be able to talk to you, but nevertheless, it gives you signs when something’s not right. A home’s windows are particularly communicative. Although they don’t last forever, high-quality, well-maintained windows could last for 20 years or more, but there are many factors at play. (Windows in a coastal city like Charleston, SC, might age faster than they would in Los Angeles, CA, for example.) If your windows are more than a few decades old, listen carefully to what they’re telling you, so you’ll know when they need to be replaced.

Here’s what to be on the lookout for.

1. They’re damaged, warped, or broken

It’s sometimes possible to repair a window instead of replacing it. If your window’s problem is minor, such as needing new weatherstripping or hardware, a repair might be the best option. But replacing a damaged, warped, or broken window sash or frame is almost always preferred to attempting a repair. “Even if the windows are still operable, they can develop problems,” says Viny Guida, Senior  Manager  at Deluxe Windows. Do your windows fog up? Are they drafty? Do they stick when you try to open or close them? Do they refuse to stay open? If your windows are communicating in those ways, they’re telling you to replace them.