My double glazing unit is misted, draughty or broken. Should I repair or replace?
You’ve spotted it. That foggy patch sitting between the panes — the one you can’t wipe away no matter what you try. Or perhaps it’s the draught you’ve started feeling on your hand every time you sit near the window. Or a crack that appeared overnight after a cold snap. The moment you notice it, the same thought hits almost everyone: how much is this going to cost me? Here’s the honest answer: in the vast majority of cases, far less than you’re expecting. Most double glazing Problems don’t mean new windows. They mean a blown sealed unit — a glass-only fix that takes under an hour and typically costs between £60 and £120. But not always. And knowing which situation you’re in is exactly what this guide is for. We’ll walk you through every common problem, give you a clear repair-or-replace decision framework, and share honest 2026 prices for the High Wycombe, Oxford and Reading area — no jargon, no upselling. What’s Actually Wrong? The Three Most Common Double Glazing Problems Before you can decide whether to repair or replace, you need to know what you’re actually dealing with. Most calls The Glazing Squad receive fall into one of three categories. Here’s how to identify yours. 1. Misted or foggy glass — the sealed unit has blown This is the most common call we receive — particularly across High wycombe, Oxford and Reading, where a large proportion of homes were built between the 1970s and the mid-1990s. Original glazing from that era is now sitting right at, or well beyond, its 20 to 25-year lifespan. What’s happening inside the window: the factory-sealed unit is made of two panes of glass bonded together with a spacer bar and an airtight perimeter seal, with argon gas trapped in the cavity between them. When that seal fails — through age, expansion and contraction, or impact — the argon escapes and moisture-laden air rushes in. As temperatures drop, that moisture condenses on the inner glass surfaces. The result is the foggy, cloudy appearance you can’t wipe away from either side, because it’s sealed inside the unit. The critical thing to understand: this is a glass unit problem, not a frame problem. In most cases, the UPVC or aluminium frame around it is completely fine. You don’t need new windows. You need the failed glass unit replaced — and that’s a very different job. 2. Cold draughts – the seals or gaskets around the frame have failed This is a different problem entirely. Run your bare hand slowly around the edge of the glass where it meets the frame on a cold day. If you feel cold air moving, the rubber gasket or seal around the perimeter has degraded. Over time, these rubber seals harden, shrink and crack. The good news: gasket seal replacement is usually the most affordable repair on this list. The frame itself is fine. A glazier replaces the rubber bead, and the draught stops. It doesn’t mean the sealed unit inside has failed — though if the window is older, it’s worth having both checked at the same time. 3. Cracked or broken glass — a safety and security issue; act quickly A cracked or smashed pane is never just cosmetic. Depending on the location, it’s both a security risk — your home is easier to access — and potentially a safety risk if the glass is in a door or low-level window. Don’t leave it. Should You Repair or Replace? Here’s the Honest Answer This is the question everyone reading this page actually wants answered. So let’s get straight to it. The decision comes down to one thing: is it the glass that’s failed, or the frame? If the frame — the UPVC, aluminium or timber surround — is solid, undamaged and sealing properly, almostall double glazing problems are repair jobs. A new sealed unit is manufactured to the exact measurements ofyour existing frame, fitted inside it, and the job is done. Your frames stay. Your costs stay low. f the frame itself is warped, cracked, soft to the touch, or showing rot, then even a perfect new glass unit willfail again — because the frame can no longer hold a proper seal. That’s when replacement becomes the rightcall. One local context worth knowing: a significant proportion of homes across High Wycombe, Aylesbury and thewider Chilterns were built between the 1970s and 1995. Double glazing installed during that period is nowbetween 30 and 50 years old — well past its rated lifespan. If your home is from this era and you’re seeingseveral windows misting at the same time, it’s worth discussing full replacement rather than patching units oneby one. We’ll always give you the honest assessment 5 Signs Your Double Glazing Needs Replacing, Not Repairing Repair is almost always the right answer when only the glass unit has failed. But there are specific situations where full replacement is the smarter long-term investment. Here are the five signs to look for. 1. The frame itself is warped, soft or cracked. Press your thumb gently along the frame. If the UPVC gives, feels spongy, or has visible cracking, the structure is compromised. A new sealed unit won’t seal properly inside a failing frame — you’d be spending money for a temporary fix at best. 2. You’ve had the same window repaired before and it’s failed again. A recurring failure on the same unit usually means the frame seal has degraded to the point where it can no longer hold a new unit properly. The unit keeps failing because the root cause — the frame — hasn’t been addressed. 3. Multiple windows are misting at the same time. When three, four or five windows all fail within the same season, it’s a clear age-related signal. The whole installation has reached the end of its life together. Patching them one by one costs more over three years than a full replacement done once — and you lose the energy efficiency gains of
