Window Seal Repair Cost (2026 UK Guide)
Window seals play a crucial role in insulation and energy efficiency. When seals fail, condensation can form between panes, draughts may develop, and heating bills can increase.
This 2026 UK guide explains average window seal repair costs in the UK, what affects pricing, and when replacing the sealed unit is necessary.
Average Window Seal Repair Cost
| Issue | Repair required | Average UK cost |
|---|---|---|
| Replace rubber gasket seal | Fit new perimeter seal | £80 – £200 |
| Reseal window frame | Remove and apply new sealant | £100 – £250 |
| Replace blown double glazed unit | Fit new sealed unit | £200 – £500 |
| Reseal timber window | Remove and reapply sealant | £150 – £350 |
| Draught proofing treatment | Install sealing strips | £80 – £180 |
| Small window full reseal | Supply and fit new seals | £120 – £300 |
For a full overview of related repairs, see our Windows & Doors Repair Cost Guide.
What Causes Window Seal Failure?
Window seals deteriorate over time due to exposure and movement.
Common causes include:
- Age-related wear
- UV exposure
- Frame expansion and contraction
- Poor installation
- Moisture ingress
- Extreme temperature changes
Once the seal in a double glazed unit fails, moisture enters the cavity and causes misting.
Signs Your Window Seal Needs Repair
Seal problems often show visible symptoms.
Look out for:
- Condensation between panes
- Draughts around the window
- Shrinking or cracked rubber seals
- Increased outside noise
- Rising energy bills
- Visible gaps between frame and wall
If condensation is inside the glass unit, full sealed unit replacement is usually required.
What Affects Window Seal Repair Costs?
Several factors influence pricing.
Window type
uPVC seal replacement is usually cheaper than timber frame resealing.
Extent of failure
Minor perimeter seal replacement is affordable.
Blown double glazing requires full unit replacement.
Accessibility
Upper-floor windows may require ladders or scaffolding.
Glass size
Larger sealed units increase material cost.
DIY checks you can safely do
- Inspect rubber seals for shrinkage
- Check for visible cracks in sealant
- Confirm condensation is inside the glass
- Feel for draughts on windy days
- Take photos before requesting a quote
Avoid removing sealed units without proper tools.
When this is an emergency
- Glass has cracked due to seal failure
- Severe draughts during extreme weather
- Water is entering around the frame
- Security is compromised
- Mould growth is spreading due to moisture
Prompt repair prevents further insulation damage.