Windows do more than just provide light, ventilation, and a view of the exterior. If you listen, they’ll let you know when something is wrong. Here are six things your windows are trying to tell you.

If condensation forms on the interior of the window, especially in the corners or along the bottom, this indicates a high indoor humidity level. Condensation is most likely to occur here when it’s freezing outside because air cools near the glass, causing the moisture it contains to condense into a liquid.

To prevent water damage, crack the window slightly for 15 minutes to improve ventilation. Then, avoid this problem in the future by running a dehumidifier, turning on the kitchen and bathroom exhaust fans, and venting the dryer to the exterior.

THE WINDOW SEAL HAS BROKEN

If condensation forms between the sheets of glass, this means the double- or triple-pane window has a broken seal. Moisture has found its way in through the leak and caused your windows to fog up. A broken seal negates the insulating benefits of a multi-pane window, so you should have the panel replaced as soon as possible.

THE WOOD FRAME IS SWELLING

Is your double-hung wood window difficult to open and close? It could be trying to tell you that the wood has started swelling in response to high humidity. Simply sanding down the wood panes should help them slide more easily all year round despite changes in the weather.

THE WINDOW NEEDS TO BE CLEANED

When a casement window becomes difficult to open and close, it likely means the moving parts need to be oiled or replaced. A sliding window may grate along the track if debris has collected there. This is easy to remedy by quickly vacuuming the track with a brush attachment. Sticky weatherstripping can also cause windows of all types to stick. Wipe it with a damp cloth to restore smooth operation.

THERE’S A WATER LEAK SOMEWHERE

Your first thought might be that, if water is getting in through the window during a rainstorm, it isn’t closing tightly. This could be the problem if water collects in the track, but if the leak is located at the top of the window, water is probably getting in through the roof or siding and dripping down the wall to the window. Don’t ignore this because it could lead to mold growth, poor air quality, and structural problems.