A good set of window frames can last 20 years or more with proper care and maintenance. But there comes a time in every window’s cycle when it’s time to replace it with a better, newer model. Here are some of the signs you can look for when deciding whether to upgrade your own.

Check your windows for signs of damage. Inspect your frames for cracks, gaps and other wear. Do they fog up? Do they stick, requiring a bit of elbow grease to open them? Repair minor problems without replacing the entire window. “A window restoration specialist like Coviello—or even a good handyman or carpenter—can free up painted-shut upper sash, replace broken panes, sash cords, hardware, and glazing … and add weather-stripping,” Josh Garskof writes for Time. That sort of fix is likely to run you $100 to $350 per window. But, warped, cracked or otherwise badly damaged frames should be replaced instead of applying a band-aid to the problem. “Even if the windows are still operable, they can develop problems,” Kris Hanson, Senior Group Manager in Product Management at Marvin Windows and Doors, tells Forbes.