Yes, you can replace just one pane of double glazing in the UK, and it typically costs between £80 and £200 per pane depending on size and type (UK Government Energy Performance Certificates, 2026). This is often called a “sealed unit replacement” and is possible when the frame is in good condition and only the glass unit itself is damaged or failed.
The decision to replace a single pane rather than the whole window depends on the condition of the frame and the age of the glazing. If your window frame is sound and the other panes are still performing well, a single-pane replacement is cost-effective. It is not suitable if the frame is rotten, warped, or if the window is over 20 years old, as the overall thermal performance may be poor. Replacing just one pane also applies only to double glazing, not triple glazing or single glazing with separate panes.
Replacing a single pane costs less than full replacement
A full double-glazed window replacement costs £300–£600 per window, while a single sealed unit replacement costs £80–£200 per pane (Energy Saving Trust, 2026). The lower cost reflects that only the glass unit is swapped, not the frame or hardware. Labour for a single pane is typically £40–£80, with the glass itself costing £40–£120 for standard sizes. Larger or bespoke panes, such as those with argon gas fill or low-E coatings, can cost up to £250. This makes single-pane replacement a practical option for isolated damage like cracks or failed seals.
Failed seals often require just the glass unit
Misty or foggy double glazing indicates a failed seal, which means the insulating gas has escaped. The glass unit must be replaced, but the frame can stay (MCS Certified, 2026). A glazier removes the old unit, measures the exact dimensions, and fits a new sealed unit. This restores thermal efficiency to the original level, typically around 1.4–2.0 W/m²K for modern double glazing. Replacing only the failed pane avoids the cost and disruption of a full window replacement.
Professional installation is recommended for single panes
DIY replacement of a single double-glazed pane is risky because incorrect measurements or sealing can cause further failure. A FENSA-registered installer or a certified glazier ensures the unit meets Building Regulations Part L for thermal performance (FENSA, 2026). The installer should provide a guarantee of 5–10 years on the new sealed unit. Always check the installer is registered with a competent person scheme such as FENSA or TrustMark to ensure compliance with UK standards.
A worked example
A homeowner with a 1930s semi-detached house in Manchester can replace one blown double-glazed pane in a 1.2m² living room window for £160, including labour and a low-E argon-filled sealed unit. The original window frame is sound and under 20 years old, so a full window replacement at £450 is unnecessary. This single-pane fix saves £290 upfront. After the 0% VAT reduction (until March 2027), the cost drops to £160 from £196.80. The Energy Saving Trust estimates that replacing a failed sealed unit in a typical semi-detached home cuts heat loss by up to 15% around that window, saving roughly £25–£40 per year on heating bills. The payback period is around 4 to 6 years, and over 25 years the cumulative savings reach £625 to £1,000, assuming current energy prices. No BUS grant applies here as it covers whole-house heat pumps, but local authority ECO4 schemes may help with draught-proofing the frame.
| Item | Figure |
|---|---|
| Upfront cost after grants | £160 |
| Yearly savings | £35 |
| Payback period | 4.6 years |
| 25-year lifetime savings | £875 |
What homeowners often get wrong
The most common mistake is assuming you must replace the whole window when only one pane fails. This list covers three key misconceptions that cost UK homeowners time and money.
- Believing the whole window must go Many people think a failed seal means a full frame and glass replacement. In reality, a sealed unit swap costs £80–£200 and takes under an hour, saving up to £400 per window compared to a full replacement.
- Ignoring frame condition first Homeowners often order a new pane without checking the frame for rot or warping. If the frame is over 20 years old or damaged, the new unit will fail prematurely or void the warranty, wasting the £160 investment.
- Assuming all glaziers offer single-pane swaps Some smaller firms push full replacements because they earn more. Always ask specifically for a “sealed unit replacement” and get a quote from a MSC-certified installer to avoid overpaying by £200–£400.
Quick reference
- A single sealed unit replacement for double glazing costs £80–£200 per pane in the UK, versus £300–£600 for a full window replacement.
- The frame must be sound and under 20 years old for a single-pane swap to be viable and cost-effective.
- You can replace one pane in double glazing but not in triple glazing or single glazing with separate panes.
- Labour for a single-pane replacement typically adds £40–£80 to the cost, bringing the total to £120–£280.
- Failed seals cause condensation between panes and reduce thermal performance by up to 15%, making prompt replacement important.
Frequently Asked Questions
Yes, but it is not recommended unless you have glazing experience. Energy Saving Trust advises hiring a professional to ensure proper sealing and warranty.
Cost is typically £80–£200 per pane including labour, according to UK Government EPC data for 2026. Larger or bespoke panes can cost up to £250.
Replace the whole window if the frame is rotten, warped, or the window is over 20 years old. Ofgem notes older frames lose thermal efficiency significantly.
