How Much Does Sash Window Restoration Cost?

Somewhere between £700 and £1,100 per window, plus access, plus VAT. That is the honest headline for a proper sash restoration in London in 2026, and if a quote for a whole house comes in well under it, something has been left out.

The interesting question is not the average. It is why the window on your half-landing costs three times what the one in the back bedroom does, and whether the difference is justified. Here is how the money actually breaks down.

What "restoration" means, and what it doesn't

The word gets used for three quite different jobs, and the price gap between them is enormous.

Overhaul. The sashes come out, the beads come off, the cords and weights are renewed, the pulleys are cleaned or replaced, paint build-up is dressed off the running surfaces, and the sashes go back sliding properly. No new timber unless something is obviously gone. On a typical London window this is roughly £280 to £480 per window, and it takes a joiner about half a day once he is set up.

Full restoration. Everything above, plus timber repair where decay has started, re-puttying, draught sealing throughout, new staff and parting beads, and redecoration inside and out. This is what most people mean, and it is where the £820 to £1,020 per window figure sits on a specialist's price list, before VAT and before access.

Replacement joinery. New sashes made to match, or a whole new window in the existing box frame. From about £820 for a single made-to-match sash to £2,000-plus per window for a complete new unit. That is a different budget entirely and we treat it separately in our guide to what replacement really costs.

The confusion is deliberate on some quotes. A firm quoting "restoration" at £350 a window is quoting an overhaul, and you will find out about the rot and the decorating later.

Line items: what each job costs on its own

These are London ranges, excluding VAT, for a firm that does this work properly. Prices from a general builder will be lower and the work usually is too.

Two things about that table. First, notice how expensive a single-window visit is compared with the per-window rate on a whole house. Almost every firm has a minimum charge — £400 to £500 plus VAT is common in London — because half the cost of a small job is getting a van and two people to your street and parked. If you have one broken cord, wait until you have three things to do.

Second, the cill items. The cill is the part that fails first because it is horizontal, exposed and usually the last thing anyone paints properly. A splice repair at £180 is cheap; a full cill replacement at £450 is not, and the difference is often eighteen months of neglect. That is the whole argument in repairing a rotten frame by splicing rather than replacing.

Room by room: what a real London house needs

Take a standard three-bedroom Victorian terrace — the kind that runs in ranks through Walthamstow, Peckham, Tooting and Acton. Eight or nine openings, eleven or twelve sashes. This is roughly how the money lands.

Add VAT at 20% on most of it and external access on top. A whole-house restoration on a London terrace realistically lands between £11,000 and £17,000 all in. That is a genuinely large number and it is why phasing the work is normal.

Three rooms deserve explaining.

The bay. A canted bay is the most expensive single feature in the house, and not because the joinery is harder. It is because there are three windows in a curved run, the cills sit under a lead or tiled roof that channels water at them, and the whole assembly moves as one when the front of the house settles. Bays are also where the original glass most often survives, which slows everything down.

The half-landing. Small window, big price. It sits over a stairwell with a drop beneath it, which means a proper working platform inside rather than a pair of steps, and it is frequently the only window in the house that has never been opened since the war. Expect the sashes to be painted solid and the pockets to be full of a century of debris.

The bathroom. If there is rot anywhere in the house it is here, because a bathroom generates a litre or two of water vapour a day and it condenses on the coldest surface, which is the glass, and then runs down onto the bottom rail and sits in the putty line. Nine times in ten the bottom rail and the cill need work. Our article on wet rot in sash windows explains why the failure always starts in the same three places.

The costs that are not on the window

This is where quotes diverge and arguments start.

Access. Anything above first floor on a street elevation needs scaffolding or a tower. A single elevation on a London terrace typically runs £650 to £1,100 for a standard hire period, and if the scaffold stands on the pavement you need a licence from the borough, usually £50 to £200. Some firms include it, most do not. Ask.

Parking. Genuinely a line item in inner London. A suspended bay or a daily permit in a controlled zone can add £30 to £80 a day to a job, and specialist price lists openly charge more for jobs where the van cannot get near the house.

Paint condition. Paint on an older window is very likely to contain lead, which rules out dry sanding and burning off. Chemical stripping or controlled infrared costs more in time and consumables, and if the previous decorator built up eight coats over unsound primer, the stripping is the job rather than a preliminary to it. The order of work when painting sashes matters more than the paint you choose.

Hidden decay. No surveyor can see inside a mortise and tenon joint from a ladder. A good quote will carry a provisional sum for timber repairs found on removal, and a good contractor will show you the decayed section before he cuts it out.

Glass. If the original cylinder glass survives, budget for it to break. It is thin, uneven and 130 years old, and even careful de-glazing loses the odd pane.

VAT: the saving most people miss

Restoration labour and materials are standard-rated at 20%. There is no relief for listed buildings — the old zero rate on approved alterations was withdrawn years ago and is not coming back.

But draught stripping for windows and doors is currently zero-rated as an energy-saving material when supplied and installed in domestic property, and that relief runs to 31 March 2027, after which it reverts to 5%. On a house where the draught-proofing element is £4,000 of a £12,000 job, that is £800 that does not need paying. Secondary glazing and double glazing are explicitly excluded from the relief and stay at 20%.

Separately, if the property has genuinely been unoccupied for the two years before work starts, a VAT-registered contractor can charge 5% on the whole renovation under the empty dwelling rules. You will need evidence — council tax records, a letter from the borough's empty property officer — and the certificate has to be in the builder's hands before he starts. Worth checking if you have just bought a probate house.

Ask any quoting firm to break out the draught-proofing element separately. Some do it automatically. Most do not until asked.

Where the money is worth spending

If the budget will not stretch to everything, spend it in this order.

1. Anything with active water ingress. A soft cill or a failed putty line is getting worse every week. Everything else can wait a year; this cannot.
2. Draught-proofing. The gaps around an average sash window add up to the equivalent of a hole ten square inches or more. Sealing them is the cheapest comfort you will ever buy, and it pays back in a fraction of the time a replacement window does. If you are considering doing it yourself, read where the DIY route goes wrong first.
3. The rooms you sit in. Restore the reception rooms and the main bedroom properly. The box room can be overhauled and left.
4. External decoration. Paint is the maintenance system, not the finish. A window repainted on a five to seven year cycle will outlive three sets of uPVC.
5. Glazing upgrades. Last, and only once the joinery is sound. Putting a sealed unit into a sash with a decaying bottom rail is money set on fire.

Getting a quote you can actually compare

Ask every firm for the same three things and the comparison becomes easy.

A written schedule, window by window, saying what is being done to each — not a single lump sum for "restore 12 windows". A separate line for access and a separate line for decoration. And a stated provisional sum for hidden timber repair, with a rate for how it will be charged if it is needed.

Then ask each surveyor to open every sash while he is there. The ones who do are the ones whose price will not move.

If you want the individual job prices rather than the whole-house picture, our breakdown of what each repair should cost covers them one by one, and our sash window restoration service works across every London borough if you would rather have someone come and put numbers against your own windows.