In short: a full overhaul-and-draught-proof — sashes out, all four cords renewed, sashes eased, new parting and staff beads carrying brush pile, pile routed into the meeting rails — costs roughly £250–£400 per window nationally and £330–£590 per window in London for a standard size. A whole Victorian terrace of 8–12 sashes is therefore around £3,000–£7,000. Quotes of £80–£150 a window are for sticking a brush strip on the existing beads, which is a different piece of work.
The headline numbers
Prices below are collected from published UK cost guides and specialist price lists, with the source and date named in every case. They are guide ranges for budgeting, not a quotation — a real price comes from a survey, because the condition of the timber is the single biggest variable.
| Price | What it covers | Area | Source |
|---|---|---|---|
| £248–£388 average £318 | Draught-proofing line item in a sash refurbishment: brush seals fitted into the sash channels and around the meeting rail | UK average | National trade directory cost guide, 2026 |
| £328–£588 | Full service on a small/medium sash (under 1.8m high, under 0.9m wide): replacement cords, new window furniture, timber mouldings with pre-installed carrier and pile | London | London specialist price list, dated March 2025 |
| £488–£888 | The same service on a large sash, or a sash on spiral balances | London | London specialist price list, March 2025 |
| £788–£1,288 | Curved sash | London | London specialist price list, March 2025 |
| £888–£1,388 | Venetian sash — two fixed side panels, cords running through a machined groove in the head | London | London specialist price list, March 2025 |
| £200–£450 | Draught proofing, with a full terrace of 8–12 windows quoted as a batch | London | London joinery firm, 2026 |
| from £320 + VAT | Draught proofing following a survey | Regional | Regional specialist, 2026 |
| £900–£1,500 | An entire sash bay, depending on size and access | London | London specialist price list, March 2025 |
Note that the London specialist figures carry a March 2025 date on their own page, so treat them as slightly historic. London full-service pricing clusters around £330–£590 for a standard window; national line-item pricing clusters around £250–£400.
Why two quotes for "draught proofing" can differ fivefold
This is the thing worth understanding before you compare anything. The phrase "draught proofing" is used for two completely different pieces of work.
The strip-down (£250–£590 a window)
The staff beads come off, both sashes come out, the parting beads are levered out of their grooves in the pulley stiles, the weight pockets are opened and all four cords renewed. The sashes are eased so they run freely and so the meeting rails come back into alignment. A groove is routed for the pile carrier — an 8mm straight flute cutter is the commonly reported size — and new parting and staff beads carrying pile in a carrier are fitted. The sashes are re-hung, re-balanced for the added friction, and the hardware is renewed.
The stick-on (£80–£150 a window)
A self-adhesive brush strip is applied to the existing beads. Nothing is removed, nothing is eased, no cords are touched. On a sound, well-fitting window this does something useful. On a window that has dropped, been painted many times, or has worn beads, it will not seal, because the gap it needs to bridge varies along its length. You can do the same thing yourself for a few pounds — see our DIY guide.
Neither is dishonest. What is misleading is quoting one price against the other. Ask any prospective installer two questions: are the sashes coming out? and are the parting and staff beads being replaced?
What changes the price of your window
- Size. Anything above roughly 1.8m high or 0.9m wide moves into a higher bracket.
- Type. Spiral-balance, Venetian and curved sashes are all more, because the mechanism or geometry is different.
- Condition. Rot in the cill or the base of the stiles has to be repaired first — see below.
- Number of windows. The single biggest lever. Most of the cost is skilled time and set-up.
- Access. Upper floors, bay windows and difficult parking all add time.
- Decoration. Routing and rebating exposes bare timber that needs priming; whether the installer redecorates is a big line item.
One honest nuance from a London specialist worth repeating: around four out of five installations fall in the lower-to-mid part of their published brackets. The top of a range is usually the difficult window, not the typical one.
What a whole house costs
Multiply, then take something off for doing them together. A Victorian terrace with 8–12 sashes at full-overhaul prices lands around £3,000–£7,000.
Watch out for a genuine source conflict here. The Energy Saving Trust puts professional draught proofing of a whole home at around £250, and consumer cost guides at roughly £200–£250. Those figures are for generic foam and brush strips around the doors and windows of an ordinary house. They are not the price of overhauling a house full of box sashes. Any site quoting £250 next to sash overhaul work is comparing two different jobs.
Repairs and extras
Historic England is explicit that windows should be assessed for repairs before any draught proofing, and notes that straightforward repairs on their own can cut air infiltration and heat loss by up to a third. Sealing over a rotten cill just hides it.
| Work | UK average | London specialist |
|---|---|---|
| Cill replacement | £160–£320 (avg £240) | £250–£450 |
| Cill splice | £120–£240 (avg £180) | £180–£300 |
| Stiles / front cheeks | £120–£240 (avg £180) | £160–£300 |
| Replacement sash | £270–£400 (avg £335) | £400–£800 |
| Replacement lower rail only | — | £180–£300 |
| All four sash cords, on an existing visit | ~£150 | — |
| Sash cords as a standalone callout | ~£70–£80 per cord | £280–£480 |
| Repainting a sash window and frame | £200–£500 | £240–£520 per side |
| Double glazing an existing sash | £650–£1,300 | £680–£1,280 |
| Full sash window refurbishment | £620–£920 (avg £770) | — |
| New timber sash window installed | from £1,450 | £2,080–£3,380 |
Common paid extras alongside draught proofing are security restrictors and sash stops (around £40 a set), replacement furniture such as a Brighton fastener and sash lifts (around £40 a set), and internal or external redecoration. If external decoration is on your list anyway, doing it while the sashes are out is genuinely good value — it avoids a separate access cost.
If you are having the glazing upgraded at the same time, budget for re-balancing: Historic England notes double glazing can add up to four times the weight of single glazing, so the counterweights have to change.
Minimum charges are real
Almost every specialist has one, and it catches people out. One London firm publishes a minimum callout of £500 plus VAT, prices single and two-window jobs on a separate higher scale, and quotes £940 plus VAT for an emergency callout including the first two hours. If you have one draughty window, you are likely paying a disproportionate amount for it. It is usually worth waiting until you can do several.
VAT — and why "5%" is out of date
Several competitor sites still say draught proofing attracts 5% VAT. Under HMRC VAT Notice 708/6, a zero rate applies to the installation of specified energy-saving materials in residential accommodation from 1 May 2023 to 31 March 2027; from 1 April 2027 these revert to the reduced rate of 5%. Draught stripping is on the qualifying list, defined as strips fixed around windows, interior and exterior doors and loft hatches to reduce draughts.
Two caveats that matter. The relief applies to the installation service and to materials supplied by the installer — materials a homeowner buys to fit themselves are standard-rated at 20%. And where draught proofing is done alongside other work, the single-supply and multiple-supply test in the notice determines the rate, so a full overhaul-and-repair job will not automatically be zero-rated in its entirety. Ask your installer to set out the VAT treatment on the quote rather than assuming it.
Is it worth the money?
It depends entirely on what you are buying it for, and we would rather be straight about this than win work on a number that does not survive scrutiny.
On energy alone, at full overhaul prices, no. The Energy Saving Trust's current figure is around £55 a year (about £80 in Northern Ireland) for draught proofing a whole home's windows, doors and floors. Against £3,000–£7,000 of sash work the payback is decades. You will find sash-industry pages quoting £80, £125 or £145 a year — those are older Energy Saving Trust figures from a period of higher energy prices, and they are not what the Trust publishes now.
On comfort, rattle, dust, noise and keeping the original windows, yes. Measured testing recorded up to an 86% reduction in air infiltration on a professionally draught-proofed sash, and Historic England reports 33–50% less air leakage from windows generally. Draughts also make a room feel colder than it is, which is why people turn the heating up. The rattle fix is mechanical and reliable rather than an estimate.
What it does not do is insulate. In guarded hot box testing the U-value of a sash window moved from 4.5 to 4.2 W/m²K after draught proofing — a difference inside the measurement uncertainty. If cold glass is your complaint, secondary glazing is the measure that actually moves the number.
How to compare quotes properly
- Ask whether the sashes are being removed. This single question separates a £150 job from a £400 one.
- Ask whether new parting and staff beads are included, or whether the existing ones are being reused.
- Ask whether all four cords are being renewed, or only broken ones.
- Ask whether the price includes easing and re-balancing — a seal on a misaligned sash just binds.
- Ask what happens if rot is found, and get the repair rates in writing before work starts.
- Ask who does the making good and priming where timber has been routed.
- Check the minimum charge and whether your job clears it.
- Ask for the guarantee on the pile — five years is common, with roughly ten years' service expected in practice.
If you would like a written guide price for your own windows, tell us how many sashes you have and your postcode and we will come back to you — see contact, or read what the service includes first.