Sash windows cost £600–£3,500 per window installed in 2026, depending on the frame material and window size. uPVC sash windows are the most affordable at £600–£1,200, while softwood timber costs £1,200–£2,500 and hardwood heritage sash windows reach £1,800–£3,500. A full-house replacement for a typical 3-bed Victorian terrace with 6 windows costs £4,500–£18,000 depending on specification.
We compared pricing from UK sash window specialists and cross-referenced quotes with trade databases. This guide covers sash window costs by material and mechanism type, repair versus replacement, planning permission for listed buildings and conservation areas, energy efficiency upgrades, and how to get the best quotes.
Sash windows are among the most expensive window types to replace because of their sliding mechanism and the specialist skills required. However, repair or restoration is often viable for £150–£800 per window – far less than full replacement – and is usually the preferred approach for period properties where the original character must be preserved.
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- uPVC sash windows cost £600–£1,200 installed - timber starts at £1,200 for softwood, £1,800+ for hardwood heritage specifications
- Full-house replacement costs £4,500–£18,000 - for a 3-bed Victorian terrace with 6 windows (uPVC to hardwood timber)
- Repair costs £150–£800 per window - broken cords, draughty sashes, and localised rot can all be fixed for a fraction of replacement cost
- Listed buildings and conservation areas require planning permission - uPVC is almost always refused; timber or slim-profile aluminium is typically required
- Colour and finish add 30–50% - white uPVC is cheapest; woodgrain foils, RAL colours, and heritage finishes carry significant premiums
Sash Window Costs by Material
Sash window prices vary dramatically by frame material – more so than casement windows because sash mechanisms require precise engineering and the sliding action demands tighter tolerances. The table below shows typical costs for a standard-sized sash window (600mm × 1,200mm), supply and install.
| Material | Cost Per Window (Installed) | Lifespan | Maintenance |
|---|---|---|---|
| uPVC | £600–£1,200 | 20–35 years | Low (occasional cleaning) |
| Softwood timber | £1,200–£2,500 | 40–60 years | High (repaint every 3–5 years) |
| Hardwood timber | £1,800–£3,500 | 60–100+ years | Medium (repaint every 5–7 years) |
| Aluminium | £1,200–£2,800 | 35–45 years | Very low |
uPVC sash windows replicate the sliding motion of traditional sashes using spring balance mechanisms rather than cords and weights. They are the most affordable option and require virtually no maintenance, but they have thicker frame profiles than timber, which reduces the glass area and can look less authentic on period properties. Many conservation areas refuse uPVC sash windows.
Timber sash windows are the traditional choice and the only option accepted in most listed buildings and conservation areas. Softwood (typically Scandinavian redwood) is the standard choice for new timber sashes, while hardwood (oak, accoya, or sapele) costs 50–70% more but requires less frequent maintenance and lasts significantly longer. The ongoing cost of maintaining timber – repainting every 3–5 years at £200–£500 for a full house – is a significant factor over the window’s lifetime.
Aluminium sash windows offer the slimmest frame profiles of any material, closely matching the sightlines of original steel-framed windows. They are increasingly specified for conservation areas where the slim profile of the original windows must be replicated but timber is not practical. Aluminium requires minimal maintenance and lasts 35+ years.
Sash Window Costs by Mechanism Type
The operating mechanism affects both the cost and the authenticity of sash windows. This is a distinction that most cost guides overlook, but it significantly impacts the price – particularly for period property owners who need to replicate the original mechanism.
| Mechanism | Cost Premium | How It Works | Best For |
|---|---|---|---|
| Spring balance | Standard (base price) | Concealed springs counterbalance the sash weight | Modern replacements, uPVC sashes |
| Cord and weight (traditional box sash) | +20–40% | Lead weights on cords inside a box frame | Listed buildings, heritage restoration |
| Spiral balance | +10–20% | Tensioned spiral mechanism in the frame | Slim-profile timber sashes |
Traditional cord-and-weight sash windows require a full sash box – a deeper frame that houses the counterbalance weights on cords running over pulleys. This mechanism has been used since the Georgian period and is often required in listed buildings to maintain authenticity. Replacing a cord-and-weight sash costs 20–40% more than a spring balance equivalent because the full sash box must be replaced, which involves more extensive removal and fitting work.
Spring balance sash windows are the modern standard. The springs are concealed within the frame, making them easier and cheaper to manufacture, install, and maintain. If your property does not have heritage restrictions, spring balance sashes offer the best value.
Sash Window Repair vs Replacement Costs
Repairing existing sash windows is often significantly cheaper than full replacement and is the preferred approach for period properties where the original frames have architectural or heritage value. Below is a comparison of common sash window repairs versus replacement costs.
| Issue | Repair Cost | Replace Cost | Recommendation |
|---|---|---|---|
| Broken sash cord | £80–£150 | – | Always repair |
| Draughty / rattling sashes | £150–£350 (draught-proofing) | – | Repair first – draught-proofing saves ~£80/yr |
| Rotten timber sill | £200–£500 (splice repair) | – | Repair if rot is localised |
| Single glazed → double glazed | £300–£600 (slim DG unit into existing frame) | £600–£2,500 | Depends on frame condition and heritage rules |
| Failed sealed unit (misted) | £120–£250 | – | Repair unless frame is also damaged |
| Severely rotten frame (30%+ rot) | – | £1,200–£3,500 | Replace – frame integrity compromised |
| Spring balance failure | £80–£200 | – | Always repair |
A useful rule of thumb: repair if the frame is structurally sound and rot covers less than 30% of the frame. Replace if rot is extensive, the frame is warped, or you are upgrading from single glazing and the existing frame cannot accommodate slim double glazed units. For listed buildings, repair and restoration is almost always preferred by conservation officers over replacement. For more detail on common repairs, see our double glazing repairs guide.
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Planning Permission for Sash Windows
Replacing sash windows like-for-like does not normally require planning permission under permitted development rights. However, sash windows are disproportionately found in period properties – and many of these are in conservation areas or are listed buildings, where planning rules are significantly stricter.
Conservation areas: Replacement windows must match the original in material, profile, and opening style. uPVC is frequently refused because its thicker frame profile does not match the slim sightlines of original timber sashes. You will typically need timber or slim-profile aluminium. Check with your local planning authority before ordering – installing non-compliant windows can result in enforcement action requiring removal at your cost.
Listed buildings: Full Listed Building Consent is required for any window changes, including like-for-like replacement. uPVC is almost always refused. Heritage-specification timber sash windows with traditional cord-and-weight mechanisms are usually required, adding 20–40% to the cost. The consent application is free but takes 8–12 weeks.
Before ordering sash window replacements for a period property, contact your local conservation officer. They can advise on acceptable materials and profiles before you commit to a purchase. Replacing windows without the required consent in a conservation area or listed building is a criminal offence and can result in prosecution, fines, and a requirement to reinstate the original windows.
Full-House Sash Window Replacement Costs
A complete sash window replacement for a typical period property is a significant investment. The table below shows project costs for a 3-bed Victorian terrace with 6 sash windows, which is the most common scenario.
| Specification | 6-Window Cost (Installed) | Notes |
|---|---|---|
| uPVC, white, spring balance | £4,500–£7,200 | Budget option; may not be accepted in conservation areas |
| Timber softwood, painted, spring balance | £9,000–£15,000 | Standard heritage-acceptable option |
| Timber hardwood, heritage cord and weight | £14,000–£21,000 | Full heritage spec for listed buildings |
| Aluminium, slim profile | £9,000–£17,000 | Modern alternative for conservation areas |
Upper-floor sash windows may require scaffolding (£600–£1,200 for a typical terrace frontage). Add £200–£500 for colour or woodgrain finishes on uPVC, or 30–50% on timber for non-standard paint colours. Volume discounts of 10–15% are common when replacing all windows in a single order. Lead time from order to installation is typically 2–4 weeks for uPVC and 6–10 weeks for bespoke timber.
Energy Efficiency and Savings
Replacing single-glazed sash windows with double-glazed equivalents saves £140–£150 per year on heating bills for a typical 3-bed house (source: Energy Saving Trust). Draught-proofing existing sash windows – without replacing them – saves around £80 per year at a cost of £150–£350 per window, making it a faster payback option.
Modern double glazed sash windows achieve a U-value of 1.2–1.4 W/m²K, meeting current Building Regulations (Part L). Slim double glazed units (12–16mm total thickness) can be fitted into existing timber sash frames without replacing the frame itself, costing £300–£600 per window – a good compromise for listed buildings where full replacement is not permitted. For energy efficient window options and available grants, see our dedicated guides.
What Affects Sash Window Prices?
Beyond material and mechanism type, several factors can move the price significantly.
Window size. A standard sash (600mm × 900mm) is the base price. Large stairwell or landing sash windows (1,000mm × 1,400mm+) can cost 50–80% more due to the increased glass area and heavier sash weight requiring stronger mechanisms.
Colour and finish. White uPVC and painted white timber are the cheapest options. Woodgrain foils on uPVC add 10–20%. RAL colour powder coating on aluminium adds 10–15%. Heritage paint colours on timber (matching original period colours) add 30–50% – the premium reflects specialist paint systems and the multiple coats required.
Decorative bars. Astragal bars (applied to the glass surface to replicate multi-pane Georgian sashes) add £50–£150 per window. Georgian bars (set within the sealed unit) cost slightly less but look less authentic from close up.
Glass specification. Standard double glazing is the default. Low-E coated glass adds £30–£50 per window for better thermal performance. Argon gas fill is usually included as standard. Acoustic glass adds £50–£100 per window. Toughened safety glass is required by Building Regulations for any glazing below 800mm from floor level.
For a full breakdown of window costs across all types, see our complete double glazing cost guide. Use our free cost estimator for an instant price estimate, or see our best window companies for vetted national installers. If your sash windows need repair rather than replacement, see our repairs guide for costs by fault type.
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