Replacing your sash windows can transform your home and reduce your energy bills.

Discover sash window replacement costs by material, glazing and job type, plus what affects the price, and when restoration is a better choice than full replacement.

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How much does it cost to replace sash windows?

The average cost to replace a sash window is £1,300 per window. That said, costs will vary depending on material choice, window size and accessibility.

Let's get started by looking at one of the biggest price factors: the material used.

Sash window costs by material: uPVC, timber and aluminium

The material you choose is the biggest single factor in your final cost. Here's how each option compares:

1. uPVC sash windows cost:

• Cost: uPVC sash windows cost between £600 and £1,200 per window for supply and fit

• Pros: They're the cheapest option and need very little maintenance. No painting, no staining, just an occasional clean

• Cons: The trade-off is authenticity. uPVC profiles are thicker than timber and can look out of place on older properties. Some conservation areas and listed buildings prohibit uPVC entirely

2. Timber sash windows cost:

• Cost: Timber sash windows cost between £1,000 and £3,000 per window depending on whether you choose softwood or hardwood. Softwood (such as pine) sits at the lower end; hardwood (such as oak or accoya) is at the top

• Pros: Timber is the only material permitted in most listed buildings. It can be repaired rather than replaced and, with proper maintenance, can last 50–100 years

• Cons: The downside is upkeep: timber needs painting or staining every 5–7 years

See our cost of timber windows guide for a full breakdown.

3. Aluminium sash windows cost

• Cost: Aluminium sash windows cost between £800 and £1,500 per window. They sit between uPVC and timber on price and combine slim sightlines with low maintenance

• Pros: Aluminium doesn't rot or warp, and it holds its shape over decades. The look is more contemporary than timber, which suits some properties better than others

• Cons: Reduced thermal efficiency compared to uPVC, and might not suit period homes

For a full cost comparison, see our cost of aluminium windows guide. Or contact a sash window fitter directly for an exact quote.

Find sash window installers near you

Download our free mobile app to connect with checked and reviewed sash window fitters covering your local area and get an exact quote for the job.

Or read on to learn how adding double glazing can impact the costs above.

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Cost of replacing sash windows with double glazing

Once you've decided on the material for your sash windows, you need to decide whether to opt for double or triple glazing.

For most sash window replacements, double glazing is the practical choice. Let's look at the cost, pros and cons:

• Cost: Replacing a sash window with double glazing costs around £1,300 per window

• Pros: Slim-profile double-glazed units are the standard choice for period properties. They keep the narrow sightlines that characterise traditional sash windows while delivering modern thermal performance

• Cons: Significantly increases how much you'll pay

See our full double glazing cost guide for a detailed breakdown.

Sash window replacement cost: job estimator tool

Not quite ready to contact a tradesperson, but want to learn more about the costs involved?

Try our free interactive cost calculator for an instant estimate based on the size and number of sash windows you need replacing.

Job Estimate Calculator

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Sash window restoration cost

If your sash windows are in relatively good nick overall, restoration could be an option.

The average sash window restoration cost is £284 - a big difference in price compared to replacing them.

Our sash windows refurbishment price guide takes you through the costs and steps involved.

Sash window repair costs

If you're lucky, it might turn out that your sash windows just need repairing. Here's some common repair costs:

• The average sash window cord repair cost is £140 (for a replacement)

• The average cost of draught proofing sash windows is £300

However, you're always best off contacting a sash window repair specialist for an exact quote.

Factors affecting the cost of replacing sash windows

Several variables push the price up or down from the average. Consider each of these when budgeting:

• Materials used: Timber, uPVC or aluminium each have different price points. Timber is the most expensive, uPVC the cheapest

• Size of windows: Larger windows need more materials, so the price rises with size

• Complexity of design: More complex designs and glazing bar patterns cost more than plain windows

• Type of glazing: Single, double or triple glazing all affect the final cost

• Number of windows: More windows means higher material and labour costs

• Accessibility: Windows that are hard to reach take longer to install. Upper-floor windows often need scaffolding

• Conservation area or listed building status: Specialist installation and planning requirements push costs up, particularly for timber replacements

• Location: London and the South East are more expensive due to higher labour rates

Sash windows in conservation areas and listed buildings

Is your home in a conservation area or listed? Conservation-approved replica sash windows can be more complicated and costly. Here's the key things to know about:

• Planning permission: Listed buildings usually require consent and like-for-like timber replacements

• Higher costs: Specialist timber windows, planning applications and bespoke joinery can increase costs. Expect to pay £1,500–£3,000+ per window

• Heritage uPVC: In some conservation areas, heritage uPVC sash windows may be accepted if they closely match the original design, but always check with your local planning authority first

• Grants: Some listed and heritage properties may qualify for funding for energy-efficiency improvements. Check current government and local authority schemes before starting work

Signs you need to replace your sash windows

If your sash windows haven't been touched in 15 or 20 years, the frames may be beyond restoration. Here's the most common signs that it's time for a replacement (or, if you're lucky, a repair):

• Noticeable draughts from windows

• Window seals failing (extensive warping and cracks)

• Rotten timber frames

• Damp and mould

An experienced sash window specialist can talk through your options as to whether repair or replacement is best.

Are sash windows worth the cost?

For period homes, sash windows are hard to beat on authenticity and long-term value. Here's what you get for the price:

• Authentic look for period homes: can't be replicated by other window types

• Increase property value, particularly in Victorian and Edwardian houses

• Low maintenance when properly fitted

• Versatile: available in uPVC, timber and aluminium

• Wood-framed options are environmentally friendly

• Improved security with modern locking systems

• Energy savings with double or triple glazed units

Can I replace sash windows myself?

Sash window replacement is not a DIY job for most homeowners:

• Windows are heavy and awkward to handle

• You must comply with building regulations

• Getting a draught-free, leak-free finish without professional tools and experience is very difficult

• Installation requires training and the right tools

• Working at height with heavy windows is dangerous

For safety, security and a long-lasting finish, hiring a professional is best.

Finding a sash window installer near you

Use our quick and easy request a quote feature and we will get experienced local window installers to contact you directly. To get accurate quotes, be as detailed as you can:

• How many windows need replacing

• The window material you prefer (uPVC, timber or aluminium)

• Whether you want single, double or triple glazing

• Whether your property is in a conservation area or is listed

• Which floor the windows are on (ground floor or upper floor)

You can also browse sash window installers in your area below:

Why use Checkatrade?

• Checked - Every Checkatrade member must pass up to 12 checks and commit to upholding the Checkatrade Standard

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Sash window replacement: key things to know

Before you hire a sash window installer, use this checklist to make sure you're prepared and know what to expect:

Sash window replacement: Cost checklist

• It's possible to refurbish old sash windows, and this should be done every 10 years or so to keep them in good condition

• Draught proofing, installing curtains and restoring sash windows are all ways to reduce draughts from older windows

• Replacing sash windows is not a recommended DIY job for safety reasons

• Get a selection of quotes from Checkatrade-vetted window installers before committing

• Check whether your property is in a conservation area before choosing a material

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