These are approximate prices rather than fixed quotations. Checkatrade’s June 2026 guide places a typical double glazed casement window at around £500–£1,250 and a sash window at around £700–£1,500, while other current guides place straightforward UPVC replacement windows nearer £400–£800.

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The average cost of new windows for a particular home will depend on the combination of products required. A house with simple UPVC casements may cost considerably less than one containing timber sashes, large bays and bespoke glazing.

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What Affects New Window Costs?

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Window size

Larger windows require more frame material, glass and reinforcement. Very large or heavy units may also require additional installers or specialist lifting equipment.

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An unusually tall, wide, curved or shaped window will generally cost more than a standard rectangular frame.

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Number of opening sections

Fixed glazing is normally less expensive than a window containing opening sections.

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Costs can increase where the design includes:

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• Multiple opening casements

• Tilt-and-turn mechanisms

• Fire-escape openings

• Restrictors

• Specialist hinges

• Additional locking points

• Sliding sash mechanisms

Two windows with the same external dimensions can therefore have very different prices.

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Frame material

The choice between UPVC, timber, aluminium and composite frames has a significant effect on the overall window replacement cost.

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Glass specification

Standard energy-efficient double glazing is usually less expensive than specialist glass.

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Additional costs may apply for:

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• Triple glazing

• Toughened safety glass

• Laminated security glass

• Acoustic glazing

• Solar-control glass

• Obscure or patterned glass

• Self-cleaning coatings

• Georgian or leaded designs

• Slim heritage glazing

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Different rooms may require different specifications. Bathrooms may need obscure glass, while low-level windows and panes beside doors may require safety glazing.

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Colour and finish

Standard white UPVC is generally one of the most economical choices.

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Grey, black, coloured and woodgrain finishes normally cost more. Dual-colour frames, with one finish externally and another internally, may carry a further premium.

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Timber windows can be supplied painted, stained or naturally finished. Bespoke colours and multi-coat factory finishes can increase the price.

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Installation access

Straightforward ground-floor installations generally cost less than upper-floor windows positioned above conservatories, extensions or sloping roofs.

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Additional costs may arise from:

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• Scaffolding or access towers

• Restricted parking

• Difficult delivery routes

• Large or heavy glass units

• Specialist lifting equipment

• Working around shutters or fitted furniture

• Restricted internal access

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The quotation should confirm whether scaffolding and access equipment are included.

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UPVC Window Costs

 

UPVC windows are usually among the most affordable options for home window replacement.

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The price will depend on:

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• Window dimensions

• Frame profile

• Number of opening sections

• Standard or flush casement design

• White, coloured or woodgrain finish

• Locking system

• Glass specification

• Energy rating

• Ventilation requirements

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A simple white UPVC casement will normally cost less than a flush casement, coloured frame or UPVC sash window.

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Products that look similar may have different reinforcement, seals, locking systems and energy performance. Comparing only the price can therefore be misleading.

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Timber Window Costs

 

New wooden windows generally cost more than standard UPVC because of the materials, manufacturing processes and joinery involved.

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Timber options include:

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• Engineered softwood

• Hardwood

• Oak

• Sapele

• Accoya and other modified timber

• Traditional box sash windows

• Flush casement windows

• Bespoke heritage designs

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Timber is particularly suitable for period homes, listed buildings and conservation-area properties where traditional materials and detailing are important.

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Although the initial cost may be higher, good-quality timber windows can be repaired and redecorated during their service life.

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Aluminium Window Costs

 

Aluminium windows usually cost more than standard UPVC but provide slim frames, strong construction and a contemporary appearance.

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They are commonly chosen for:

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• Modern homes

• Extensions

• Large glazed openings

• Picture windows

• Contemporary bay windows

• Properties requiring narrow sightlines

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Aluminium prices depend on the frame system, thermal performance, colour, opening arrangement and size of the glass.

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Large aluminium windows may also require specialist handling because of their weight.

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Sash Window Replacement Costs

 

Sash windows are generally more expensive than conventional casements because they contain additional frame sections and sliding mechanisms.

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The cost will be influenced by:

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• UPVC or timber construction

• Spring balances or traditional cords and weights

• Standard or slim double glazing

• Georgian glazing bars

• Decorative sash horns

• Bespoke mouldings

• Draughtproofing

• Historic or listed-building requirements

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Current guides place double glazed sash windows at approximately £700–£1,500, while bespoke timber sash replacements can range from around £1,000 to £3,000 per window.

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Before replacing an original sash window, it may be worth considering repair, draughtproofing or secondary glazing. Retaining the original frame can sometimes be more appropriate for the property and may reduce the amount of disruptive work required.

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Bay Window Replacement Cost

 

Bay windows cost more than standard flat windows because they contain several connected sections and may form part of the structure supporting the building above.

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A replacement may require:

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• Reinforced corner posts

• Temporary structural support

• New cills

• Insulation around the bay

• Roof or canopy repairs

• Internal boarding and plastering

• External trims and sealants

• Several connected window units

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A June 2026 UK cost guide gives an average bay window replacement cost of approximately £2,000, with three-, four- and five-section UPVC bays generally increasing in price according to their size and complexity.

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Larger timber, aluminium or specialist bay windows can cost considerably more. A proper survey should establish whether the existing frames support masonry, floors or roofing before removal begins.

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Whole-House Window Replacement Cost

 

The total cost of replacing windows throughout a house cannot be estimated accurately from the number of bedrooms alone.

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Two three-bedroom houses may contain completely different window arrangements. One might have eight simple casements, while another includes:

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• A large front bay

• Several sash windows

• French or sliding doors

• Coloured aluminium frames

• Difficult upper-floor access

• Specialist acoustic or security glass

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A whole-house quotation should include a window schedule identifying the size, material, opening style and glass specification for every unit.

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Installing several windows as one project may reduce the average cost per window because surveying, manufacturing, delivery and labour can be organised together.

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Replacing Glass Instead of the Complete Window

 

Condensation or misting between the panes usually means that the seal around the double glazed unit has failed.

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Where the frame remains sound, it may be possible to replace only the sealed glass unit. This will normally cost less than replacing the complete frame.

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Glass-only replacement may be suitable where:

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• The frame remains secure

• Hinges and locks operate correctly

• There is no significant distortion or decay

• The window is not excessively draughty

• The existing frame still provides reasonable insulation

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Complete window replacement may provide better value where the frames are rotten, warped, insecure or no longer suitable for modern glazing.

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Additional Costs to Check

 

A quotation should clearly state whether it includes:

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• Removal of the existing windows

• Disposal and recycling

• New cills

• Internal trims

• External sealants

• Plaster repairs

• Redecoration

• Scaffolding

• Safety glass

• Trickle vents

• Structural support

• Certification

• Parking charges

• VAT

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Some installers include minor making good but exclude final decoration. Older homes may also reveal concealed damage after the original frames have been removed.

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Allowing a reasonable contingency can help cover unexpected repairs to timber, plaster, brickwork or lintels.

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Comparing New Window Quotes

 

Obtain detailed quotations based on the same specification.

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Each quotation should identify:

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• Frame material and profile

• Window dimensions

• Opening arrangement

• Glass specification

• U-value or energy rating

• Frame colour and finish

• Handles and locking systems

• Ventilation

• Safety-glass locations

• Removal and disposal

• Internal and external making good

• Installation programme

• Product guarantee

• Workmanship guarantee

• Certification arrangements

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A quotation stating only “supply and fit new windows” does not provide enough information for a proper comparison.

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Large headline discounts and limited-time offers should also be treated carefully. The final price, specification and installation standard matter more than the claimed saving.

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Building Regulations and Certification

 

Replacement windows in England and Wales must comply with relevant Building Regulations.

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A FENSA-approved installer can self-certify qualifying replacement work, register the installation and provide a certificate showing that it complies with the applicable requirements.

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Where the installer is not registered with an appropriate competent-person scheme, a separate Building Control application may be required.

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Keep all certificates and guarantees safely, as they may be requested when the property is sold.

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Getting an Accurate Window Replacement Cost

 

Online prices are useful for early budgeting, but a reliable quotation requires a survey.

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The installer should inspect:

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• Every window opening

• Existing frames and cills

• Brickwork and lintels

• Bay-window supports

• Internal finishes

• Access arrangements

• Ventilation

• Safety-glass requirements

• Escape-window requirements

• Planning restrictions

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This allows the proposed windows to be priced accurately and reduces the likelihood of additional charges after installation begins.

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Find Trusted New Window Installers

 

The cost of new windows should be considered alongside energy performance, security, appearance and installation quality. A properly measured and carefully fitted window can provide better comfort and long-term value than a cheaper product installed to a lower standard.

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APN Double Glazing can connect homeowners with experienced local installers offering UPVC, timber, aluminium, sash and bay-window replacements.

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Get in touch for expert advice and a free, no-obligation quote for your new windows.

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