7 Simple Tests to Find Out If Your Windows Need Replacing Before Winter

Before the first hard freeze, it's worth knowing which windows are doing their job and which are quietly costing you heat. Windows account for roughly 25 to 30 percent of a home's heating and cooling energy use, according to the Department of Energy, so a few failing units can make a real difference on a Maine heating bill. Here's a quick check you can run room by room. (If you want the broader overview of warning signs, start with our post on when it's time to replace your windows.)

1. The hand test

On a cold, windy day, hold your palm near the edges of the sash and frame. If you feel moving air, the window is leaking, even when it's closed and locked.

2. The flame or smoke test

Hold a lit candle or stick of incense near the frame on a breezy day, and keep it well away from curtains. If the flame flickers or the smoke streams sideways, you've found a draft. Do each window, because one bad unit can hide among good ones.

3. The paper test

Close the sash on a strip of paper. If you can pull it out without resistance, the weatherstripping or seal isn't tight. Try it in a few spots along the sash.

4. Look for fog between the panes

Condensation on the room side of the glass usually points to indoor humidity. Fog or haze trapped between the panes means the seal has failed and the insulating gas has escaped. That glass will not recover, and it's one of the clearest signs a window is near the end of its life.

5. Probe the frame for rot

Gently press a screwdriver into the lower corners of wood frames and the sill. If it sinks in or the wood crumbles, moisture has been getting in. Soft spots can also mean damage to the surrounding wall, so don't wait on these.

6. Open, close, and lock each window

Windows that stick, won't stay up, or no longer lock are a comfort and a security issue. Difficulty opening is often the first sign the frame has shifted or swollen.

7. Check the extras

Notice outside noise coming through, faded floors and furniture near big windows, ice forming on the inside of the glass, and winter heating bills that keep creeping up. None of these proves a window has failed on its own, but together they tell a story.

What your results mean

One or two minor drafts can often be fixed with new weatherstripping or caulk. Failed seals, rot, or windows that fail several tests are usually better handled by replacement. Many homeowners start with the worst offenders, such as north-facing or bedroom windows, and phase the rest.

If you're not sure what you're seeing, we're happy to take a look and give you an honest opinion, including when repair is the better choice. Lead times can run weeks to months, so a fall check-up gives you time to schedule before the deep cold.