Published 21 September 2026 · Sash Window Draught Proofing
Restoring an original sash window is almost always cheaper than replacing it, and in a Conservation Area or Grade II listed home it is often the only option a conservation officer will accept. The difficulty for homeowners is that quotes vary enormously, because "restoration" can mean anything from a half-day of draught proofing to full splice repairs and new sash cords.
This guide sets out realistic London prices for 2026, explains what drives the cost up or down, and shows where the money actually goes.
Typical London restoration costs per window
The figures below are indicative ranges for a standard two-over-two Victorian sash in a London property. Final prices depend on access, window size, timber condition and the number of windows in the order.
| Work carried out | Typical cost per window |
|---|---|
| Draught proofing only (brush seals, staff and parting bead) | £180 – £320 |
| Sash cord replacement (both sashes, new weights balanced) | £160 – £280 |
| Draught proofing plus sash cord renewal | £280 – £450 |
| Localised timber repair and splicing | £150 – £600 |
| Full restoration (strip, repair, re-cord, re-seal, re-hang) | £550 – £1,200 |
| Full replacement with a new box sash | £1,400 – £2,800 |
Most London homeowners with a whole-house project fall between £350 and £700 per window, and per-window pricing usually drops once six or more windows are done in one visit.
What drives the price
Condition of the timber
Surface decay in the bottom rail or cill is common and can be cut out and spliced with matching timber. Widespread rot, failed joints or a distorted box frame takes far longer and pushes a window towards the top of the range.
Size and glazing pattern
A large bay sash with multiple panes takes longer to dismantle, re-cord and reassemble than a small bedroom window. Margin-light and six-over-six patterns add labour.
Original glass
Where original crown or cylinder glass survives, it should be retained. Careful removal, storage and re-bedding adds time but preserves the character that makes the window worth restoring. See our guide on restoring original crown glass.
Access
Upper-floor windows on a London terrace may need internal working only, tower access or, occasionally, scaffolding. Anything beyond ladder access adds to the quote.
Heritage constraints
Listed buildings and Conservation Areas require like-for-like materials and traditional methods. This rarely adds a huge premium, but it does rule out shortcuts. Our Grade II listed draught proofing guide explains the consent position.
Restoration versus replacement
Replacement is frequently sold as the cheaper long-term option. In period London housing that is usually untrue.
- Restoration typically costs 40–60% less than replacement per window.
- Original Victorian and Georgian joinery is generally slow-grown timber that outperforms modern softwood.
- Replacement removes historic fabric and can reduce the value of a period property.
- Restoration plus draught proofing delivers most of the comfort gain at a fraction of the cost.
- Where noise or heat loss remains an issue, secondary glazing can be added afterwards without touching the original window.
What a proper restoration includes
A restoration quote worth accepting should cover:
- Removal of both sashes and inspection of the boxes, pulleys and weights
- Cutting out and splicing any decayed timber with matched species
- New waxed braided cords, with weights re-balanced to the sash
- Servicing or replacing pulley wheels
- Replacement staff bead and parting bead incorporating brush seals
- Re-puttying and re-bedding of glass where required
- Realignment so both sashes close evenly and lock securely
- Making good, priming and a tidy finish ready for decoration
If a quote omits weight balancing or bead replacement, it is a partial repair rather than a restoration.
How to reduce the cost without cutting corners
- Do the whole house in one visit rather than one window at a time
- Combine draught proofing with cord renewal, since the sashes come out either way
- Fix failing putty and paintwork early, before water reaches the joints
- Deal with condensation, which accelerates decay at the bottom rail
- Prioritise the windows on the exposed or road-facing elevation first
Frequently asked questions
How much does it cost to restore a sash window in London?
Most London sash window restorations cost between £350 and £700 per window in 2026. Draught proofing alone starts around £180, while a full strip, repair, re-cord and re-seal can reach £1,200 for a large or badly decayed window.
Is restoring a sash window cheaper than replacing it?
Yes. Restoration is typically 40–60% cheaper than fitting a new box sash, and it keeps the original timber and glass, which matters for Conservation Area and listed properties.
How long does sash window restoration take?
A straightforward window takes half a day to a day. A full restoration with timber splicing usually takes one to two days per window, though a team working through a whole house will complete several windows a day.
Do I need consent to restore sash windows in a listed building?
Like-for-like repair generally does not require listed building consent, but any change to appearance or materials may. We recommend confirming with your local conservation officer before work starts.
Will restoration stop draughts and rattling?
Yes, when brush seals are fitted into new staff and parting beads and the sashes are re-balanced. This usually removes rattling completely and cuts window-related heat loss significantly.
Get a fixed price for your windows
We have restored original sash windows across London for 15 years, from single flats to whole Grade II listed terraces. Survey and quotation are free, and pricing is fixed before work begins. See our sash window draught proofing service or contact us for a survey.