Sash Window Repair Costs — London
An overhaul and draught proof costs £188 per window, and a sill replacement costs £120 per window. Double glazing an existing sash starts at £480. The table below lists every standard price, and we always give a free written quote before work starts, because you should know the price first.
| Service | Price | What's included |
|---|---|---|
| Overhaul and draught proof | £188 per window | Sashes out, draught seal system installed on all perimeters, new sash cords, new timber profiles, new hardware. |
| Sill replacement | £120 per window | Including splicing styles. Extra if the sill runs a bay or Venetian frame. |
| Replacement sash | from £190 | More for ornate or multiple glazing-bar sashes. |
| Bottom-rail repair | £120 | Most common splice repair — primed and undercoated. |
| Small splice repair | £80 | Plus prime and undercoat. |
| Sash re-cording & counterbalance | £120 per window | Consider the fuller overhaul instead — far better value. |
| Double glazing existing sash | from £480 | Pilkington low-E unit, five-year guarantee on the sealed unit. |
| New double-glazed sash in original frame | from £680 | When the original sash can't carry a DGU. |
| Full double-glazed replacement | from £1,480 | Hard or softwood, fully decorated, modern security. |
These are typical rates, not a fixed menu. Every London home is slightly different, because age, access and timber condition vary. Scaffolding, difficult access, unusually large sashes or listed-building constraints can all change the figure.
What drives the price
The biggest factor is the condition of the timber. A sash with sound wood needs cords and seals, so it costs little. However, a sash with rot needs splicing, and that takes more time and material.
Window size and design matter too. Large sashes and ornate, multi-bar sashes take longer to make and glaze. Bay windows and Venetian frames also add work, because the sills and linings are more complex.
Access is the third factor. Upper floors may need scaffolding, and that adds cost. We look at access during the free site visit before we quote.
Which service suits which problem
If a window rattles or leaks air, start with sash window draught proofing. If it will not open or the cords have snapped, look at sash cord replacement or a full sash window overhaul. The overhaul is usually better value, because it fixes cords, seals and hardware in one visit.
Soft or rotten timber at the bottom of the frame is a sill repair job, while a rattling window needs seals. For cold rooms and noise, double glazing your existing sashes keeps the original timber. When a sash is beyond saving, we make replacement sashes to match.
Our guide to sash window repair costs in London goes into more detail because it covers typical jobs. You can also browse all our sash window services.
VAT on energy-saving work
We are a VAT-registered company, and you receive a VAT invoice. Where eligible, installing draught stripping in homes in Great Britain is zero-rated until 31 March 2027, according to HMRC's VAT Notice 708/6. However, from 1 April 2027 the notice says the reduced rate of 5% returns.
Eligibility depends on the work and the property, so we confirm the VAT treatment on each written quote. We do this because the rules differ between jobs.
Every price includes
- A free site visit and written quote.
- A five-year no-quibble guarantee on labour and the draught-proofing system.
- A VAT invoice for the work.
- Locking security restrictors on request.
Ready for a firm price? Send us your details through the contact page and we will arrange a visit.