Is Your Double Glazing Actually Doing Its Job? Signs It's Time for a Repair or Replacement

When Double Glazing Goes Wrong, Your Home Pays for It

Most homeowners don't think about their windows until something's obviously wrong. A handle that won't turn, a draught you can't explain, or that foggy film sitting between the panes that no amount of cleaning will shift. These aren't just annoyances — they're signs that your double glazing has stopped working the way it should.

The good news is that not every problem means a full replacement. Knowing what you're  actually looking at makes a real difference to what you spend and how quickly you fix it.

Condensation Between the Panes

This is the most common sign that a sealed unit has failed. Double glazed windows work by trapping an insulating layer of gas (usually argon) between two panes of glass. When the seal around that unit breaks down, moisture gets in. You end up with condensation sitting inside the window — somewhere you can't wipe it away.

A failed seal means you've essentially lost the insulating benefit of the double glazing. The window is still there, but it's no longer doing much to keep heat in or cold out. In most cases, this is a sealed unit replacement rather than a full window replacement, which is considerably cheaper.

Draughts Around the Frame

Feeling cold air coming through around your windows when they're closed? That usually points to a problem with the frame rather than the glass itself. Frames can warp over time — particularly timber ones — and uPVC frames can degrade or pull away from the surrounding brickwork. The result is gaps that let outside air straight in.

Sometimes this is fixed with resealing. Other times the frame itself needs replacing. Either way, leaving it alone isn't a neutral decision — you're heating the outside every time your boiler kicks in.

Windows That Won't Open, Close, or Lock Properly

Mechanisms wear out. Hinges stiffen, handles break, and locking points stop engaging cleanly. A window that doesn't lock properly is an obvious security issue, but it can also mean the window isn't closing flush against the frame — which brings you back to the draught problem.

Hardware repairs and replacements are often straightforward jobs. There's no need to replace an entire window because a hinge has given up.

Noticeable Noise Coming Through

Double glazing cuts down on outside noise significantly compared to single glazing. If you've started noticing that street noise or garden noise seems louder than it used to be, that could indicate a drop in the performance of your windows. A failed seal or compromised unit affects acoustic insulation as well as thermal insulation.

Rising Energy Bills With No Obvious Cause

Heating costs go up for plenty of reasons, but if your bills have crept up and you can't put it down to colder weather or a change in usage, your windows are worth looking at. Heat loss through poorly performing glazing is significant, and older or damaged units can be a real drain on what you're spending to keep your home warm.

What to Do Next

Before assuming you need a full replacement, get a professional to take a look. Many double glazing issues — failed sealed units, broken mechanisms, degraded seals — are repairable at a fraction of the cost of new windows. The key is getting an accurate diagnosis rather than guessing or putting it off.

If you're in the Bromley or Kent area and you're not sure what's going on with your windows, a no-obligation quote gives you the information you need without committing you to anything.