If your double glazing has gone misty, draughty or stiff, you're probably being told two different things: "just replace the window" and "it can be repaired." The truth is that most double-glazing faults can be repaired for a fraction of the cost of a new window — but a few genuinely can't. Here's how to tell which you need.
The short answer
If the glass or a moving part has failed but the frame is sound, repair it. You'll typically spend £55–£175 instead of £350–£900.
If the frame itself is rotten, cracked or warped, or you specifically want a big step up in energy rating, then a replacement makes sense. Otherwise, replacement is usually overselling.
Repair vs replace: the costs side by side
Prices are typical UK figures, not a quote.
| Fault | Repair (typical) | Replace (typical) |
|---|---|---|
| Misted / blown sealed unit | £55–£145 (swap the unit) | £350–£900 (whole window) |
| Worn window hinges | £75–£145 (new hinge pair) | £350–£900 |
| Broken lock or handle | £75–£175 (repair or replace) | £350–£900 |
| Rotten or cracked frame | — not repairable — | £350–£900 |
The point is the ratio: a £70 sealed-unit swap fixes the same visible problem as a £500 window replacement. The glass is the expensive-looking bit, but it's actually the cheapest thing to replace — the frame is what costs.
When repair is the right call
- The unit is misted but the frame is in good shape.
- A hinge, lock or handle has worn out.
- The window is stiff or draughty but opens and closes.
- You want the problem gone without the disruption of a full install.
When replacement is the right call
- The frame is rotten, cracked, warped or leaking water.
- The window is very old and you want to upgrade its energy rating or soundproofing.
- A full re-glaze you've planned anyway (a whole house is a different, bigger job).
Can you repair it yourself?
No, mostly. A failed sealed unit can't be DIY-fixed — it has to be swapped by a glazier. Hinges and locks can be DIY in skilled hands, but the parts must match the window's make exactly, and upstairs or heavy windows are risky to work on. If you're unsure, it's cheaper to get a professional opinion than to buy the wrong part twice.
Not sure which you need?
That's the single most common question we hear — and it's exactly the one worth asking before anyone quotes you a full replacement. Tell us what's wrong and we'll say straight whether it's a unit swap, a hinge, or genuinely a new window. Either way, you get a fixed price before any work.
Get a fixed quote — tell us what the window's doing and we'll talk you through the cheapest fix that actually works.
