If you have noticed misted double glazing in your Christchurch home — windows that look permanently foggy, steamed up or cloudy no matter how often you clean them — the good news is that this is one of the most common and most straightforward window faults we repair. It almost never means you need new windows.

At ACP Windows Ltd we are a repair-first company. Our aim is to fix the fault and keep your existing frame wherever possible, not to sell you a full window replacement you do not need. This guide explains what causes misted double glazing, why cleaning will never fix it, and how a sealed unit replacement puts it right across Christchurch and the surrounding Dorset area.

What causes misted double glazing?

Modern double glazing is made up of two panes of glass with a sealed gap between them, filled with insulating gas and kept airtight by a spacer bar and seal around the edge. When that seal fails, the unit is said to have “blown”. Two things then happen:

• Moisture gets in between the panes. Warm, damp air is drawn into the gap and, as the temperature changes, it condenses on the inside of the glass — leaving that tell-tale foggy or cloudy look.
• The insulating gas escapes. Once the seal has gone, the unit loses much of the insulation it was designed to provide.

Seals fail for all sorts of reasons: age, general wear, temperature changes over the years, or a blocked drainage system in the frame that lets water sit against the unit. Whatever the cause, once a unit has blown the problem only gets worse over time, as milky limescale deposits build up inside the glass and the view becomes permanently cloudy.

Why cleaning never clears a misted window

This is the part that catches most people out. When the misting is between the two panes, it is sealed inside the glass unit where no cloth can reach it. You can polish the inside and outside surfaces perfectly and the window will still look foggy, because the moisture is trapped in the middle. If cleaning both faces of the glass has not worked, that is a clear sign the sealed unit itself has failed.

The repair: a new sealed unit, not a new window

Here is the important bit for anyone worried about cost. A misted window does not mean you need a whole new window. In the vast majority of cases the frame is still perfectly sound — it is only the sealed glass unit inside it that has failed.

Our repair keeps your existing frame in place and replaces only the failed glass:

• We measure the opening and note the glass style and specification.
• A new made-to-measure sealed unit is manufactured to fit.
• We remove the blown unit, fit the new one, and check the seals and drainage.
• We also fix any related issues, such as a blocked uPVC drainage system, as part of the job.

Because we keep the frame, this is quicker, tidier and far less costly than replacing the whole window — and it is exactly the kind of repair we mean when we say we are repair-first. You can read more on our misted window repair service page.

What affects the cost of replacing a misted unit

Sealed units are usually priced per square metre, so the main things that affect the price are:

• The size of the glass unit
• The frame style and how the glass is held in place
• The type of glass required — for example toughened, obscure or low-emissivity glass
• How easy the window is to access
• How many units you are having replaced at once

We always give you a clear, itemised price before starting, so there are no surprises.

Local misted double glazing repairs in Christchurch

Because we cover Christchurch and the wider Dorset area, arranging a look at your misted windows is quick and easy. In many cases you do not even need a visit to get started — just email us a photo of the affected window with a short description, and we will come back to you with guidance and pricing.

If you are dealing with more than foggy glass — a stiff handle, a draught or a window that will not lock — take a look at our window repairs in Bournemouth guide too, as the same repair-first approach applies. And if you would like a professional opinion on your misted double glazing, get in touch via our Contact Us page and we will be happy to help.