When Do Windows Need Replacing?
Windows rarely fail all at once. They get a little worse each season, and because you live with them every day the change is easy to miss. This page covers what to look for, what each sign usually means, and when it is worth having someone take a proper look.
Draughts and rooms that will not hold their temperature
The clearest sign is one you feel rather than see. A room that is always colder or warmer than the rest of the house, a draught you can feel with the back of your hand near the frame on a windy day, or curtains that move when the window is shut. It usually means the seal between the sash and the frame has worn, the weatherstripping has flattened, or the frame itself has shifted. One draughty window can be adjusted. Draughts at most of the windows in the house point at age.
Fog or moisture between the panes
A double pane window is sealed, with dry air or gas between the sheets of glass. When the seal fails, moist air gets in and you see fog, condensation or a milky haze between the panes that cannot be wiped from either side. The window still keeps the weather out, but it has lost the insulation that was the point of two panes. A failed seal cannot be repaired on the glass itself. The unit is replaced, and if several windows have gone the same way in the same few years, the rest are usually not far behind.
Sashes that stick, rattle or will not stay up
A window that needs forcing open, drops shut on its own, or rattles in the frame in wind is telling you the moving parts have worn or the frame has moved. Painted shut sashes on older wood windows are common and sometimes freeable, but a window that has swollen or warped so that it no longer sits square is a different matter. Beyond the nuisance, a window that will not open properly is an exit you cannot use, which matters in a bedroom.
Soft, cracked or peeling frames
Press a wood frame at the bottom corners, where water sits longest. If it gives under a thumb, the wood is rotting from the inside. On vinyl, look for cracks, warping or a chalky surface that comes off on your hand. On aluminium, look for pitting and corrosion. Paint that will not stay on a frame is usually moisture getting in behind it. Frame damage matters more than glass damage, because the frame is what holds the window in the wall, and a frame that has gone usually means a full frame replacement rather than an insert.
Bills that keep climbing
Windows are a large share of the surface a house loses heat through, and old single pane glass or failed double pane units lose a lot of it. If your heating and cooling bills have risen without a change in how you use the house, and the windows are old, they are a reasonable place to look. It is not proof on its own, because insulation, the roof and the heating system all play a part, but it is a sign worth adding to the others.
When age alone is enough
Most replacement windows are built to last somewhere around twenty to thirty years, and climate, exposure and the quality of the original installation all move that figure. Single pane windows and the aluminium frames common before the 1990s are working much harder than anything made since. If your windows are past twenty years, they are worth having looked at even when nothing is obviously wrong, because the useful question at that point is not whether they have failed but how much life is left.
FAQ
Common questions
Do windows on one side of the house wear out faster?
Generally somewhere around twenty to thirty years, though climate, sun exposure, the frame material and the quality of the original installation all affect it. Windows on the side of the house that takes the most weather tend to age first.
Can fogged glass be fixed without replacing the window?
The glass unit itself cannot be resealed. In some windows the sealed glass unit can be swapped while the frame stays, which is cheaper than a new window. Whether that makes sense depends on the age and condition of the frame, which is what a contractor looks at first.
Is a draughty window always a sign it needs replacing?
No. Worn weatherstripping can be replaced, a sash can be adjusted and gaps around the frame can be sealed. One draughty window on an otherwise sound set is usually a repair. Draughts at most of the windows in the house are usually an age problem rather than a repair problem.
Can I check my own windows?
Most of the useful signs are easy to check. Feel for draughts on a windy day, look for fog between the panes, open and close each window, and press the bottom corners of wood frames with a thumb. Anything that needs a closer look at the frame or the wall around it is worth leaving to someone who does it every day.
My windows look fine. Is there any reason to have them looked at?
If they are past twenty years, or single pane, yes. The point of looking early is not to find a failure but to find out how much life is left, which turns an eventual replacement into something you plan rather than something that happens in the middle of winter.
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