Sash Window Repair Costs UK — What to Charge for Sash Window Restoration and Draught Proofing in 2026

Types of sash windows you will encounter

The most common type is the traditional box sash, also called a double-hung or double-hung box sash window. It has two sliding sashes held in a hollow box frame by sash cords running over pulleys and connected to cast-iron weights concealed in the weight pocket. This is the window found in almost every Victorian and Edwardian terrace in the country and the one that generates the most repair work.

Sliding sash windows are a simplified modern variant with no weight pocket. Instead they use spring balances or spiral balances to support the sash. These are more common in post-war and 1970s–1990s housing and are generally cheaper and quicker to service because access to the mechanism is simpler.

Yorkshire sash windows, found mainly in the north of England, slide horizontally rather than vertically. They are simpler in construction, rarely have weights, and are less likely to need specialist draught proofing. They do still need cord or track maintenance and are prone to rattling in the frame when the brushes or seals wear out.

Common repairs and what to charge

Sash cord replacement

Replacing broken or frayed sash cords is the most frequent callout for sash window specialists. A single sash (top or bottom) takes around one to two hours including removing the staff bead, taking the sash out, replacing the cord, reweighting, and refitting the bead. Charge £80–£150 per sash. If both sashes need doing at the same time — which is almost always advisable because the second cord will not be far behind — price at £150–£250 per window. You save travel and set-up time, the customer saves a second callout, and you can make the job worthwhile without squeezing your rate.

Use waxed cotton sash cord for authentic restoration work on heritage properties. Braided polyester cord is more durable and appropriate where longevity is prioritised over strict authenticity. Material cost for a pair of cords per window is typically £4–£10.

Draught proofing

Draught proofing is the highest-margin sash window repair. The job involves routing channels into the parting bead and staff bead, then pressing in a Schlegel-style pile seal (also called Q-Lon pile or brush seal). Done properly it eliminates virtually all cold air infiltration through the sliding sashes and the meeting rail. Supply and fit for a standard double-hung box sash window runs £200–£400 per window. Smaller windows at the lower end, large bay windows or those needing significant bead replacement at the top end.

The pile seal itself costs around £8–£15 per linear metre. A typical sash window requires three to five metres. The routing tool is a specialist purchase (around £80–£150 for a decent dedicated draught proofing router bit and jig) but once bought it pays for itself on a handful of jobs. Charge your full day rate for draught proofing work: this is a skilled, specialist job and should not be priced as general joinery.

Spiral balance retrofit

Where a box sash window has been converted to use spring or spiral balances instead of the original cord-and-weight system, or where a customer wants to eliminate the weight pocket entirely, a spiral balance retrofit is the solution. Spiral balances are fitted into the side of the sash and bear against the frame, removing the need for cords and weights entirely. The job takes two to four hours per window and should be priced at £150–£350 including materials. Note that purists and conservation officers often prefer original cord-and-weight operation to be maintained, so always check the preference before suggesting a spiral balance conversion on a heritage property.

Broken glass replacement

Single glazed glass replacement in a sash window runs £80–£200 depending on pane size and glass specification. Standard 4mm float glass is cheap; restoration glass (which mimics the slight imperfections of original crown glass) costs significantly more and is required by some conservation officers for listed building work. Always price glass replacement as a fixed cost per pane rather than a labour-only rate so you are not exposed to glass price movements between quoting and completing.

Putty re-bedding and glazing beads

Failed putty is common in older sash windows where the original linseed oil putty has dried, cracked, and fallen away. Re-bedding a pane in fresh linseed oil putty takes one to two hours depending on the amount of old putty to remove. Charge £60–£120 per pane. If the customer wants timber glazing beads instead of putty (a common request on painted softwood sashes) add the cost of the bead material and the additional time to mitre and pin the beads. Glazing beads also make future glass replacement easier, which is a genuine selling point.

Rotten sill replacement

Window sills take the worst of the weather and are often the first component to rot on an otherwise sound window. A new sill in softwood or hardwood (oak or engineered timber for durability) including cutting out the old sill, preparing the reveal, fitting, and priming runs £150–£350 per window. Hardwood sills sit at the upper end of that range. If the rot has spread into the pulley stile or the lower rail of the frame, the job becomes a significantly larger repair and should be quoted separately — see full restoration below.

Staff bead and parting bead

Staff beads and parting beads get damaged, painted over multiple times, and sometimes simply rot. Replacement is a quick job at £50–£100 per window for supply and fit. It is worth quoting this as an add-on whenever you are on site for cord replacement or draught proofing, because the beads need to be removed anyway and replacing them takes only a small amount of additional time.

Full sash window restoration

A full restoration combines every element: stripping the sashes and frame, repairing or replacing rotten timber, re-glazing as needed, fitting new cords and weights (or spiral balances), routing and fitting draught proofing seals, rehanging the sashes, and priming or painting ready for decoration. This is the premium service that commands £400–£1,200 per window.

The lower end of that range applies to smaller windows in good condition where the main work is draught proofing and cords. The upper end applies to large windows with significant rot, multiple broken panes, and complex hardware — or where specialist restoration glass is specified. For a standard Victorian terrace with eight to twelve sash windows, a full house restoration programme typically falls between £4,000 and £10,000 depending on condition and specification.

Always quote full restoration per window, not per day. Quoting per day gives the customer the impression that you are watching the clock and leaves your margin exposed if the job runs over. Per-window pricing makes the quote clear, professional, and easy to compare against alternatives like replacement.

Why repair, not replace

The case for repairing original sash windows is strong and worth communicating clearly to customers when quoting. Victorian and Edwardian timber frames were made from slow-grown softwood with much tighter grain than modern plantation timber. This makes them denser, more durable, and more resistant to rot when properly maintained. A well-restored sash window can last another 50 to 100 years. Modern replacement windows — even high-end timber sash replacements — rarely offer the same longevity.

The cost comparison also favours repair in most cases. A like-for-like replacement double-glazed UPVC sliding sash costs £800–£1,500 per window. Timber sliding sash replacements with double-glazed units run £1,200–£2,500 per window. Against those numbers, a full restoration at £600–£900 per window is genuinely competitive — and the customer keeps original features, avoids planning complications, and gets a better quality result.

Listed buildings and conservation areas

This is where sash window repair becomes non-negotiable rather than simply preferable. Properties in conservation areas require planning consent to change the external appearance of windows, including replacing timber sashes with UPVC or aluminium. In practice this means most conservation area properties cannot legally install replacement windows that differ from the originals without formal approval — which is rarely granted. Listed buildings require listed building consent for any alteration to windows, and consent is almost never given for replacement with modern materials.

This creates a captive market for skilled sash window restorers. Owners of listed buildings and conservation area properties have no realistic alternative. You can price accordingly — expect to charge 15–25% above your standard rates for listed building work given the care required, the documentation sometimes needed (condition reports, use of approved materials), and the fact that the customer cannot shop around as freely.

When quoting for a listed building, always check whether the local conservation officer has specific requirements around glass type, putty specification, or hardware. Some officers require written evidence that the correct materials have been used. This is additional scope and should be priced accordingly.

Energy performance and draught proofing

Unrestored sash windows are significant sources of heat loss, not primarily through the glass but through the gaps around the sliding sashes. A well-fitted Schlegel pile seal system reduces air infiltration by 85–95% and can make a noticeable difference to how a room feels in winter. This is an easy sell because the improvement is immediate and tangible.

For customers who want improved thermal performance without any visible change to the window, secondary glazing is the other option. An independent inner frame fitted behind the existing sash achieves near-double-glazing performance and significantly reduces noise as well as heat loss. Supply and fit for secondary glazing runs £200–£500 per window depending on the system and opening method. Slim-profile systems designed for conservation areas (where they must be removable and leave no permanent mark on the original frame) sit at the upper end.

Offering draught proofing and secondary glazing together as a package makes sense on most restoration projects. Draught proofing alone handles air infiltration; secondary glazing adds thermal mass and noise reduction. Many customers who start with cord replacement end up commissioning a full draught proofing programme once they understand the benefits.

Tools and materials

Sash window work requires a relatively modest specialist toolkit but the tools need to be right. Key items include a dedicated draught proofing router bit and guide (for cutting the pile seal channel accurately), a sash pocket chisel (for opening the weight pocket cover cleanly without splitting the frame), a hacking knife and glazing knife for putty work, and a set of decent chisels for timber repairs.

Materials to stock on your van for sash work: waxed cotton sash cord (3mm and 4mm), braided polyester sash cord, Schlegel Q-Lon pile seal in standard sizes, sash window pulleys (brass or steel), cast-iron sash weights (worth keeping a selection), linseed oil putty, and a range of softwood moulding profiles for staff bead and parting bead replacement. Having these materials to hand saves repeat trips and lets you complete jobs in a single visit.

The specialist knowledge premium

Not every joiner can work a box sash window correctly. Many general joiners will take on the work and do it poorly — replacing cords without addressing the cause of the failure, fitting draught proofing without proper routing so the pile seal compresses immediately, or rehanging sashes without adjusting the weights for the correct balance. Customers who have had bad experiences are often willing to pay significantly more for a known specialist.

Building a reputation as a sash window specialist in your area is one of the fastest routes to a full order book at premium rates. Document every job with before and after photos, gather reviews specifically mentioning sash windows, and make sure your website and Google Business Profile make your specialism clear. Customers searching for sash window repair in your area will pay to find someone who clearly knows what they are doing.

Where to find sash window work

The highest concentration of original sash windows in the UK is in the Victorian terrace belts of major cities: inner London boroughs (Hackney, Islington, Wandsworth, Lewisham), Leeds, Manchester and Salford, Glasgow, Edinburgh, Liverpool, Bristol, and Birmingham. If you are based in or near any of these areas, the market for sash window repair is enormous. Entire streets of terraced houses have the same windows needing the same work, which means one job often leads to several more via word of mouth from neighbours.

Conservation area maps are publicly available from every local authority and are worth studying. Any property within a conservation area is a potential lead. Estate agents who specialise in period properties, property management firms looking after Victorian rental stock, and local architects working on heritage projects are all worth approaching directly. Local authority conservation officers sometimes hold a list of approved contractors or can recommend specialists to homeowners who enquire — worth introducing yourself.

Quoting tips for sash window jobs

Always inspect the box frame condition before quoting. The single biggest risk on a sash window job is discovering rot in the pulley stile or the main box frame when you open the window up. Rot in the pulley stile changes the scope from cord replacement to frame repair — a job that might be three times the price. If you cannot get proper access to inspect before quoting, build a contingency into the price or quote with an explicit caveat that additional charges apply if frame damage is found.

Quote per window, not per day. This protects your margin if the job is harder than expected and gives the customer a clear, predictable cost. It also positions you differently from a day-rate general handyman, which is the comparison you want to avoid. Sash window specialists should charge like specialists.

Where a property has multiple windows needing the same work, offer a volume rate for doing them all in one programme. A slight reduction per window on five or more windows is reasonable because your set-up costs are spread across more work and you can move efficiently from window to window. However, do not discount so heavily that you lose the premium that specialist work commands.

Include a clear payment schedule in your quote. For restoration programmes over £2,000 it is standard to take a deposit (25–33%) on acceptance and the balance on completion. Do not start work without a signed acceptance.