Double glazing is one of the best investments you can make for your home's warmth and energy efficiency. But like all things, it doesn't last forever. Here are the five key signs that your sealed units may need replacing.
1. Misting or Condensation Between the Panes
This is the most obvious sign that a sealed unit has failed. When you see condensation or a milky haze between the two panes of glass, it means the hermetic seal has broken down and moisture has entered the gap. A failed seal reduces the insulating value of the window significantly. The only fix is to replace the sealed unit — the individual glass panels cannot be separated and re-sealed.
2. Cold Draughts Around the Window
If you feel cold air coming in around the edges of a window that appears to be closed, the problem is likely with the rubber seals and gaskets around the glass, not the glass itself. Perished seals can be replaced independently of the glass unit, making this a more affordable repair. However, if the draught is coming through the glass area itself, a damaged or failed sealed unit may be to blame.
3. Difficulty Opening or Closing the Window
Windows that are hard to open or close often point to problems with the hinges, friction stays, or operating mechanisms. However, a warped or bowed frame — sometimes caused by a failed sealed unit putting additional pressure on the frame — can also cause this issue. If a window suddenly becomes much harder to operate, it's worth having it inspected.
4. Noticeably Higher Energy Bills
If your heating bills have increased without a clear explanation, failing double glazing may be a contributing factor. Modern A-rated sealed units are significantly more efficient than older or failed units. Replacing failed double glazing can reduce heat loss through the windows by up to 70% compared to single glazing.
5. Cracked or Chipped Glass
A crack in a sealed unit, however small, will allow moisture to enter between the panes and will also compromise the structural integrity of the unit. Cracked glass in a double-glazed unit should be replaced promptly. The Glass Guardian can measure, supply, and fit replacement sealed units to virtually any window size.
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