If you have noticed a foggy or cloudy appearance between the panes of your double glazed windows, you are not alone. It is one of the most common glazing problems we are called out to fix across Essex and London — and the good news is that it is usually straightforward and affordable to sort.

Our double glazing repair service covers Essex, London, Surrey, and Kent, with same-day and next-day appointments available.

Double glazed windows work by trapping a layer of inert gas (usually argon) between two panes of glass. This gas layer acts as an insulator, keeping heat in and cold out. The two panes are sealed together around the edges with a rubber or silicone seal.

Over time — typically 10 to 25 years — this seal degrades. Once it fails, moisture from the air can enter the gap between the panes. When temperatures change, this moisture condenses on the inner surfaces of the glass, creating that characteristic foggy or streaky appearance.

The misting is not on the surface of the glass — it is trapped inside, which is why wiping it makes no difference.

Yes, for several reasons:

Reduced insulation. Once the seal has failed, the argon gas has escaped and the insulating gap is compromised. Your window is no longer performing as it should, and you will be losing heat — and money — through it.

Appearance. Misted units look unsightly and can affect the kerb appeal of your property.

It will not fix itself. Unlike surface condensation, which can be managed with ventilation, a failed sealed unit will only get worse over time.

In most cases, yes. The solution is to replace the sealed unit — the glass unit itself — without touching the frame. This is a much more cost-effective option than replacing the entire window.

A glazier removes the old sealed unit from the frame, fits a new one, and reseals it. The job typically takes under an hour per window and the frame is left completely intact.

This is only possible if the frame itself is in good condition. If the frame is warped, rotten, or damaged, a full window replacement may be necessary — but this is the exception rather than the rule.

Costs vary depending on the size of the window and the type of glass required, but as a rough guide:

• Small window (e.g. bathroom): £80–£150
• Standard casement window: £120–£200
• Large picture window or patio door panel: £200–£400+

These are significantly cheaper than full window replacements, which typically start at £400–£600 per window installed.

A quality sealed unit, properly installed, should last 15–25 years. The lifespan depends on:

• The quality of the glass and spacer bar used
• The quality of the installation
• The orientation of the window (south-facing windows experience more thermal stress)
• Local weather conditions

If one sealed unit has failed, it is worth checking the others. Seals tend to degrade at a similar rate, so if one has gone, others may not be far behind. We can inspect all your windows while we are on site and advise on any that are showing early signs of seal failure.

If your double glazing is misted, do not put up with it. We cover Essex, London, Surrey, and Kent, and can usually arrange a same-day or next-day visit.

Call us on 07596 081381 or 0800 634 3117 for a free, no-obligation quote.

Related reading: What to Do When a Window Breaks · The Benefits of Toughened Glass · Window Repairs & Glazing