Sash Window Cost UK 2026: Repair, Replace & Draught-Proofing Prices
Repairing a sash window costs from £150, a full overhaul runs £350–£650, and draught-proofing is £250–£450 per window. Replacing with double-glazed softwood timber costs £1,200–£2,500 fitted, hardwood £1,800–£3,500, and uPVC sash from £600. This guide breaks down every option — repair, refurbish, replace or secondary-glaze — with real Q3 2026 figures, plus conservation-area rules.
Sash Window Cost UK 2026: Quick Answer
In 2026, the cost of a sash window depends entirely on whether you repair or replace. Repairing or refurbishing an existing sash typically costs £150–£1,200 per window — far cheaper than replacement — covering everything from a snapped cord to a full overhaul with draught-proofing and timber splicing. Replacing a sash window costs £600–£3,500 fitted: uPVC is the cheapest at £600–£1,200, double-glazed softwood timber is £1,200–£2,500, and hardwood heritage sashes reach £1,800–£3,500. For period and listed properties, slim-profile double glazing retrofitted into original frames (£600–£1,500) or secondary glazing (£180–£400) keep the historic look. Expect a 20–30% premium in London and the South East.
Jump to: Repair vs Replace · By Material · By Size · Draught-Proofing · Conservation & Listed · Cord, Pulley & Rot · Secondary Glazing · Free Quotes · FAQs
Sash Window Repair vs Replacement: Which Costs Less?
The single biggest factor in your bill is whether you keep the original frame or rip it out. For the vast majority of UK period homes, repair and refurbishment is 40–60% cheaper than full replacement and preserves the slim timber sightlines, original glass and proportions that give Georgian, Victorian and Edwardian houses their character. Replacement only makes financial sense when the box frame itself has failed, the timber is rotten beyond economical splicing, or you specifically need the thermal performance of modern factory-sealed double glazing in a property that is not protected.
Original sash windows were built from dense, slow-grown softwood that is often more durable than the fast-grown timber in many modern replacements. A well-maintained Victorian sash can last another 60–100 years after a proper overhaul, so refurbishing is frequently the better long-term value as well as the cheaper option upfront.
| Option | Typical Cost (per window) | Best For |
|---|---|---|
| Basic repair (cord, sticking sash, re-putty) | £70–£300 | Sound frame, single fault |
| Draught-proofing + cord overhaul | £250–£450 | Rattling, draughty original windows |
| Full overhaul (cords, pulleys, balancing, seals) | £350–£650 | Tired but solid windows |
| Full refurbishment (+ timber repair + redecoration) | £650–£1,200 | Some rot, peeling paint, heritage homes |
| Slim double-glazing retrofit into existing sash | £600–£1,500 | Period homes wanting warmth + original look |
| Full replacement (timber, double-glazed) | £1,200–£3,500 | Failed box frame, extensive rot |
Note: Even an extensive repair job is usually 40–70% cheaper than ordering a new window. A full-house refurbishment of six windows on a 3-bed terrace typically costs £3,000–£6,000 against £4,500–£18,000 to replace them all.
When repair wins
- The box frame is sound. If the outer box and sills are solid, you are paying only to refresh the moving sashes — the cheapest path.
- The property is listed or in a conservation area. Replacement in like-for-like timber is mandatory anyway, so refurbishment avoids costly consent battles.
- You value the original glass. Old crown and cylinder glass with its gentle distortion cannot be bought; once gone it is gone.
- Budget is tight. You can phase repairs window-by-window rather than funding a whole-house replacement at once.
When replacement wins
- The box frame has rotted or pulled away from the brickwork. Re-building a box in situ can cost as much as a new window.
- You need certified energy performance. Factory-sealed double-glazed units in a new frame deliver the lowest U-values and a FENSA certificate.
- The property is modern or unprotected. A high-quality uPVC or timber replacement can be the most cost-effective long-term answer.
Sash Window Replacement Cost by Material (2026)
If you have decided to replace, material is the biggest cost lever. The table below shows typical fitted prices for a standard double-glazed sash window in 2026. uPVC is the budget option; timber is essential for period and heritage properties; aluminium is a premium contemporary choice.
| Material | Fitted Cost (per window) | Lifespan | Maintenance |
|---|---|---|---|
| uPVC sash | £600–£1,200 | 25–35 years | Minimal — wipe clean |
| Softwood timber (Scandinavian redwood) | £1,200–£2,500 | 40–60 years | Repaint every 3–5 years |
| Hardwood timber (oak, sapele, Accoya) | £1,800–£3,500 | 50–80+ years | Repaint every 5–8 years |
| Aluminium sash | £1,200–£2,800 | 40–50 years | Very low |
Note: Hardwood costs roughly 50–70% more than softwood but needs less frequent maintenance and lasts considerably longer. Accoya — a modified softwood with a 50-year above-ground rot guarantee — bridges the gap, offering hardwood durability at closer to softwood prices.
Softwood vs hardwood timber: the real trade-off
Softwood (usually Scandinavian redwood/pine) is the standard choice for new timber sashes and the most affordable timber option at £1,200–£2,500 fitted. It paints beautifully and matches original Victorian joinery, but the paint film must be maintained every three to five years or moisture gets in and rot starts. Hardwood (oak, sapele or engineered Accoya) costs £1,800–£3,500 — about 50–70% more — but is denser, more stable and far more rot-resistant, so maintenance intervals stretch to five to eight years and the window can last 80 years or more. Over a 60-year horizon the lifetime cost of the two materials often converges once repainting is factored in.
uPVC sash windows: cheaper, but with caveats
uPVC sash windows mimic the traditional look at 40–60% less than timber and need almost no upkeep, which makes them attractive for modern and unprotected homes. The trade-offs: the frames and glazing bars are visibly bulkier than slim timber profiles, they cannot be repaired in sections (a damaged unit is replaced whole), the colour cannot be changed later, and crucially they are not normally permitted in conservation areas or on listed buildings. For a Victorian terrace in a conservation area, uPVC is rarely an option regardless of price.
| Factor | Timber Sash | uPVC Sash |
|---|---|---|
| Fitted cost | £1,200–£3,500 | £600–£1,200 |
| Conservation/listed approval | Usually accepted | Rarely permitted |
| Sightlines/authenticity | Slim, period-accurate | Bulkier profiles |
| Repairability | Section-by-section | Replace whole unit |
| Maintenance | Repaint periodically | Wipe clean only |
| Resale appeal (period home) | Adds value | Can reduce value |
Sash Window Cost by Size & Configuration
Size and the number of glazing bars (the "over" pattern) drive cost as much as material. A simple 1-over-1 sash with a single large pane is cheaper to make and glaze than an ornate 6-over-6 Georgian window with twelve individual panes and slim astragal bars. The figures below are for double-glazed softwood timber, the most common replacement specification; uPVC sits roughly 40–50% lower and hardwood 50–70% higher.
| Window Size / Type | Typical Dimensions | Softwood Fitted Cost |
|---|---|---|
| Small 1-over-1 (bathroom/landing) | approx. 600 × 900mm | £1,000–£1,500 |
| Standard 2-over-2 (bedroom) | approx. 850 × 1,400mm | £1,300–£2,000 |
| Large 6-over-6 Georgian (reception) | approx. 1,000 × 1,800mm | £1,800–£2,800 |
| Tall Victorian bay (per light) | varies, 3–5 lights | £1,500–£2,500 each |
| Full bay window (3-light, fitted) | complete assembly | £4,500–£8,000 |
Note: Bay windows are priced per light plus the structural corner posts; a curved or splayed bay costs more than a square one. Decorative horns, run-through sash horns and astragal bar patterns each add to the joinery time.
Box sash vs spring-balance sash
There are two mechanisms for holding a sash open, and they cost differently to buy and repair:
- Traditional box (weighted cord) sash: the authentic system, with cast-iron or lead weights hidden in the hollow box frame, counterbalanced over pulleys by cords. It is the smoothest to operate, easiest to repair indefinitely and required for heritage authenticity, but the box frame makes it bulkier and slightly dearer. Most period homes have this type.
- Spring-balance (spiral) sash: a modern simplified system using a spiral spring instead of weights and cords, allowing a slimmer frame and lower manufacturing cost. It suits modern installations and tight reveals, but the spring balances wear out after 15–25 years and are replaced as a unit rather than repaired. Replacement spiral balances cost roughly £40–£90 per pair plus labour.
For a like-for-like replacement in a period property, specify a box-and-cord mechanism. For a modern home or a budget project where authenticity is not a concern, spring balances reduce the price.
Sash Window Draught-Proofing & Overhaul Cost
If your sash windows rattle, stick or let in a draught but are structurally sound, draught-proofing is by far the most cost-effective improvement you can make. A specialist routs a discreet brush-pile seal into the frame and meeting rails, overhauls the cords and pulleys, and re-balances the sashes so they glide and seal properly. The result is a warmer, quieter, rattle-free window for a fraction of the cost of replacement — and it is fully reversible, so it suits listed and conservation properties.
| Service | UK Average (per window) | London / South East |
|---|---|---|
| Draught-proofing only (brush-pile seals) | £150–£350 | £250–£450 |
| Draught-proofing + cord/pulley overhaul | £250–£450 | £350–£550 |
| Full overhaul (seals, cords, balancing, ease & adjust) | £350–£650 | £450–£750 |
| Whole house (6 windows, discounted) | £1,500–£3,000 | £2,000–£3,500 |
Note: Draught-proofing currently qualifies as an energy-saving measure and attracts 0% VAT, unlike most window repair work which carries 20% VAT — a meaningful saving. Doing every window in one visit typically cuts the per-window cost by 10–20%.
Is draught-proofing worth it?
Yes, for almost every owner of original sashes. Draught-proofing a typical Victorian sash window saves roughly £80 per year on heating and eliminates the cold spots and rattling that make period rooms uncomfortable in winter. At £150–£350 per window the payback is a few years on energy alone, before you count the comfort and noise benefits. Critically, it keeps the original glass and joinery intact, so it is the heritage-friendly route that conservation officers actively prefer over replacement.
What a professional overhaul includes
- Removal of both sashes from the box and inspection of the cords, weights and pulleys.
- Replacement of any frayed or snapped cords and lubrication or replacement of seized pulleys.
- Routing of brush-pile carrier seals into the staff bead, parting bead and meeting rails.
- Re-balancing the weights so each sash holds at any position and slides smoothly.
- Easing and adjusting the beads so the sash seals without binding, then re-hanging and testing.
Conservation Areas & Listed Buildings: Rules & Costs
If your home is listed or sits in a conservation area, you cannot simply order whatever window you like — and getting it wrong can mean enforcement action and the cost of doing the work twice. The good news is that modern slim-profile and vacuum double glazing now lets you keep original frames while dramatically improving warmth, and conservation officers increasingly support this approach.
| Property Status | What's Usually Allowed | Consent Needed? |
|---|---|---|
| Grade I / II* listed | Like-for-like timber repair; slim glazing case-by-case | Listed Building Consent always |
| Grade II listed | Repair; slim/vacuum glazing into original sashes | Listed Building Consent always |
| Conservation area (not listed) | Like-for-like timber; slim DG often accepted | Check Article 4 Direction |
| Unlisted, no conservation area | Any material incl. uPVC and standard DG | Building Regs / FENSA only |
Note: An Article 4 Direction removes permitted-development rights, meaning even an unlisted house in a conservation area may need planning permission to change windows. Always confirm with your local conservation team before committing.
Slim-profile and vacuum double glazing costs
The breakthrough for period homes is glazing that is thin enough to fit existing sash rebates. Historic England's guidance supports retrofitting slim-profile or vacuum double glazing into existing sashes "where the existing glass is of no historic interest and the window frame profiles are thick enough" — achieving modern warmth with minimal alteration to the fabric.
| Heritage Glazing Option | Cost (per window) | Notes |
|---|---|---|
| Slim-profile double glazing into existing sash | £600–£800 | For a typical 6-over-6 sash |
| Vacuum glazing retrofit + restoration (central London) | £1,400–£1,500 | Best U-value in a slim unit |
| Heritage statement + architect drawings (listed) | £2,500–£7,000 | One-off, before any windows ordered |
Note: For listed buildings, the professional fees for a heritage statement and architect drawings are incurred before approval is even granted, with no guarantee of consent — budget for them separately from the window work itself.
Practical heritage tips
- Read your Conservation Area Appraisal first. It sets out exactly which features the designation protects and what changes will be resisted.
- Match the original. Glazing-bar pattern, horn detail, paint colour and the depth of reveal all matter to conservation officers; like-for-like replacement is the safest application.
- Consider secondary glazing as a consent-free fallback. Because it is reversible and does not touch the historic fabric, it is often approved where double glazing is refused (see below).
- Use a specialist heritage joiner. Standard window installers rarely have the skills or the FENSA/conservation experience for listed work.
Cord, Pulley, Weight & Rot Repair Costs
Most sash window faults are minor and individually cheap to fix — it is the labour of removing and re-hanging the sash, not the parts, that makes up the bill. Here is what the everyday repairs cost in 2026.
| Repair | Typical Cost | What's Involved |
|---|---|---|
| Single sash cord replacement | approx. £70 | Remove sash, re-thread one cord over pulley |
| Both inner cords (one sash) | approx. £95 | Includes pulley check + re-hang |
| All four cords | approx. £150 | Both sashes fully re-corded |
| Cord + pulley overhaul (one sash) | £100–£200 | Both cords, pulley lubrication, re-hang |
| Counterbalance weight re-set / replace | £60–£150 | Access pocket, adjust or swap weights |
| Epoxy rot repair (per section) | £150–£300 | Cut back, harden, fill with two-part epoxy |
| Timber splice repair (per section) | £250–£600 | New timber/Accoya scarfed in |
| Full rot repair (whole window) | £400–£800 | Multiple sections, sill or rail rebuild |
Note: The cord itself costs only a few pounds, but the sash must be lifted out of the box to re-thread it — which is why a professional cord replacement is £70 and up rather than the price of the cord.
How the weighted-cord mechanism works
Inside the hollow sides of a traditional box sash hang two pairs of cast-iron or lead weights, one pair for each sash. Each weight is tied to a cord that runs up and over a pulley wheel at the top of the frame and down to the side of the sash, so the weight exactly counterbalances the sash and lets it stay open at any height. When a cord frays and snaps, the weight drops into the bottom of the box and the sash either crashes shut or jams — the classic symptom that brings most homeowners to a specialist. Fixing it means opening the access pocket in the frame, retrieving the weight and re-threading a new cord, hence the labour cost.
Tackling rot: repair, don't always replace
Localised rot is rarely a reason to scrap a window. For surface and early-stage decay, the affected timber is cut back to sound wood, treated with a liquid hardener and rebuilt with two-part epoxy filler at £150–£300 per section. Where decay is deeper, a new piece of timber — increasingly Accoya, which carries a 50-year rot-resistance guarantee — is spliced in at £250–£600 per section. Even a window with rot in several places usually comes in well under the cost of replacement, and a good splice is invisible once painted.
Secondary Glazing: A Lower-Cost, Consent-Friendly Option
Secondary glazing fits a slim, independent pane on the room side of your existing sash window, creating an insulating air gap without altering the original window at all. Because it is fully reversible and never touches the historic fabric, it frequently needs no planning consent even on listed buildings — making it the go-to solution where double glazing is refused. It is also a strong performer for noise, cutting traffic and aircraft sound more effectively than a single double-glazed unit thanks to the wide air gap.
| Secondary Glazing Type | Cost (per window) | Best For |
|---|---|---|
| Lift-out / fixed panel | £180–£250 | Rarely-opened windows, lowest cost |
| Vertical slider (mirrors sash operation) | £220–£325 | Windows you open regularly |
| Hinged / openable casement | £250–£400 | Ventilation and easy cleaning access |
| Acoustic spec (laminated glass, deep gap) | £350–£500+ | Noisy roads, flight paths, city centres |
Note: A vertical-slider secondary unit echoes the up-and-down action of the sash behind it, so it stays usable and unobtrusive. The average secondary glazing job lands around £275–£400 per window.
Secondary glazing vs slim double glazing vs full replacement
Choosing between the three heritage-friendly routes comes down to budget, consent and how much warmth you need:
- Secondary glazing (£180–£400): cheapest, best for noise, usually consent-free, but adds a visible second frame indoors and the original window still has to be opened separately.
- Slim double-glazing retrofit (£600–£1,500): keeps a single clean window line and the original frame, good thermal gain, but needs the rebate to be deep enough and usually needs consent on listed homes.
- Full timber replacement (£1,200–£3,500): best thermal performance and a FENSA certificate, but the most expensive and the least likely to be permitted on protected properties.
For many conservation-area homeowners the smartest spend is draught-proofing plus secondary glazing — together usually under £700 per window — which delivers most of the comfort gain of replacement at a fraction of the cost while keeping the original windows untouched.
What Affects Sash Window Costs — and How to Save
Two identical-looking jobs can be priced very differently. These are the variables that move your quote up or down, and the levers you can pull to keep costs sensible without cutting corners.
| Cost Factor | Effect on Price |
|---|---|
| Location (London / South East) | +20–30% vs UK average |
| Material (uPVC → softwood → hardwood) | uPVC cheapest; hardwood +50–70% over softwood |
| Glazing-bar pattern (1-over-1 vs 6-over-6) | Ornate patterns +15–30% |
| Acoustic / low-E / decorative glass | +10–25% |
| Access (upper floors, no parking, scaffold) | +5–20% |
| Listed / heritage requirements | +£2,500–£7,000 in fees |
| Whole-house job (economies of scale) | −10–20% per window |
| VAT (draught-proofing/energy measures) | 0% vs 20% on most work |
Note: Bundling all your windows into one project is the biggest single saving most owners can make — a specialist will discount 10–20% for doing a terrace's worth in one mobilisation rather than returning for each window.
Five ways to keep the cost down
- Repair before you replace. Get a specialist to assess the box frame — if it is sound, refurbishment can save you thousands per window.
- Do the whole house at once to unlock the volume discount and a single set-up cost.
- Use the 0% VAT on draught-proofing rather than ordering new windows you may not need.
- Match the spec to the property. Don't pay for hardwood and acoustic glass on a rear bathroom window no one sees or hears.
- Get three written quotes from insured, FENSA-registered or heritage-experienced specialists and compare scope line by line, not just the headline price.
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Get My Free Quotes →Sash Window Cost FAQs
A fitted replacement sash window costs £600 to £3,500 depending on material and size. uPVC sash windows are cheapest at roughly £600–£1,200, double-glazed softwood timber sashes run £1,200–£2,500, and hardwood heritage sashes reach £1,800–£3,500. Repairing or refurbishing an existing sash window is usually 40–60% cheaper, typically £350–£1,200 per window. Expect a 20–30% premium in London and the South East.
Basic repairs such as a broken cord or sticking sash cost £70–£300 per window. Re-glazing and repainting runs £200–£500, and repairing rotten timber costs £400–£800. A full overhaul covering draught-proofing, new cords, pulleys and re-balancing is £350–£650, while a complete refurbishment with timber repairs and redecoration ranges £650–£1,200 per window.
Replacing a single sash window costs £600–£3,500 fitted. A typical 3-bed Victorian terrace with six windows costs £4,500–£18,000 for a full replacement depending on whether you choose uPVC, softwood or hardwood timber and the glazing specification. Full box-frame replacement costs more than swapping the sliding sashes alone, and replacement makes most sense when the original frame is rotten beyond economical repair.
Double-glazed timber sash windows cost £1,200–£2,500 per window fitted for softwood and £1,800–£3,500 for hardwood. uPVC double-glazed sash windows are cheaper at £600–£1,200. To keep original frames in a period property, slim-profile or vacuum double glazing retrofitted into the existing sashes costs roughly £600–£1,500 per window. Acoustic or low-E upgrades add a further 10–25%.
Draught-proofing a single sash window costs £150–£350 across most of the UK, rising to £250–£450 in London. The price usually includes brush-pile seals plus an overhaul of the sash cords and pulleys in the same visit. Draught-proofing qualifies as an energy-saving measure and currently attracts 0% VAT, unlike most other window work at 20% VAT. Doing a whole house at once typically cuts the per-window cost by 10–20%.
Repair is usually better when the box frame is sound, the timber is mostly solid, and you value the original joinery, because refurbishment costs 40–60% less than replacement and keeps a period property authentic. Replacement is more sensible when the frame is extensively rotten, the box has failed, or you need certified modern double glazing and the property is not protected. Original Victorian and Georgian softwood sashes were made from slow-grown timber that often outlasts modern replacements when maintained.
uPVC sash windows are 40–60% cheaper than timber, typically £600–£1,200 fitted versus £1,200–£3,500 for timber. uPVC needs almost no maintenance and offers similar energy efficiency. However, it is not normally permitted in conservation areas or on listed buildings, its sightlines are bulkier than slim timber bars, and it cannot be repaired in sections. For period and heritage properties, timber remains the required and longer-lasting choice.
Often yes, but the type matters. The usual approach is to retain the original timber sashes and retrofit slim-profile or vacuum double glazing, which Historic England supports where the existing glass has no historic interest and the frame is thick enough. Listed Building Consent is required for any glazing change to a listed property, and heritage statements or architect drawings can add £2,500–£7,000 before windows are ordered. Always check your Conservation Area Appraisal and any Article 4 Direction first.
Replacing a single sash cord costs around £70, both inner cords on one sash about £95, both outer cords about £115, and all four cords roughly £150. A cord-and-pulley overhaul covering both cords on one sash, pulley lubrication and re-hanging is £100–£200. The cords carry hidden counterbalance weights inside the frame, so when a cord snaps the sash must be removed from the box to re-thread it — which is why labour, not the cord itself, drives the cost.
Repairing rotten timber costs £400–£800 per window on average. For early-stage surface rot, decayed wood is cut back, treated with hardener and rebuilt with two-part epoxy filler at £150–£300 per affected section. For deeper decay, a new piece of timber is spliced in at £250–£600 per section. Accoya, a modified softwood with a 50-year rot-resistance guarantee, is increasingly used for splice repairs because it resists future decay.
Yes — secondary glazing cuts draughts, noise and heat loss without altering the original window, making it ideal for conservation areas and listed buildings where consent for double glazing is hard to get. It fits a discreet independent pane on the room side. Costs are £180–£400 per window: lift-out panels from £180–£250 and vertical sliders that mirror the sash operation at £220–£325. It usually needs no consent because it is reversible and does not touch the historic fabric.
Sash windows cost 20–30% more in London and the South East than the UK average. Demand is concentrated there because of the density of Victorian, Georgian and Edwardian period housing, many properties sit in conservation areas requiring specialist heritage joinery, and labour, access, parking and congestion charges all add overheads. A draught-proofing job that costs £150–£350 in much of the country typically runs £250–£450 in inner London.
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