These figures are general budgeting guides rather than fixed prices. Window dimensions, opening sections, glazing, access and frame finishes can all change the final quotation. Current UK cost data places the average twelve-window UPVC installation at approximately £7,500, but individual properties may fall well above or below that figure.

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A small fixed window may cost considerably less than a large opening containing several casements. Similarly, a house with simple rectangular windows will normally cost less to complete than one containing bays, arches, sash windows or bespoke frame shapes.

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What Affects Replacement Window Costs?

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Number and size of windows

The number of windows has a major effect on the total cost, but size is equally important.

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Larger windows require more glass and frame material. They may also need additional reinforcement, stronger hinges and more installers to lift them safely into position.

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A quotation should therefore identify the dimensions and configuration of every window rather than providing only one overall figure.

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Fixed and opening panes

A fixed pane is normally less expensive than an opening window because it contains fewer moving parts.

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Costs may rise where a window includes:

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• Several opening casements

• Tilt-and-turn mechanisms

• Sliding sash components

• Fire-escape openings

• Restrictors

• Specialist hinges

• Additional locking points

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Two windows of similar size may have noticeably different prices because one has a simple fixed pane while the other contains several opening sections.

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Frame material

The material used to manufacture the frames will influence both the price and appearance of the replacement windows.

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Glazing specification

Standard energy-efficient double glazing will normally cost less than specialist or high-performance 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 coatings

• Obscure or decorative glass

• Georgian or leaded patterns

• Slim heritage glazing

• Self-cleaning glass

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The most appropriate glass may vary throughout the property. Bathrooms may require obscure glazing, while panes close to doors or floor level may need safety glass.

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Colour and finish

Standard white UPVC is generally one of the least expensive options.

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Grey, black, coloured and woodgrain finishes usually carry an additional cost. Dual-colour frames, with different finishes inside and outside, may cost more again.

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Timber windows can be factory painted or stained. Bespoke colours and detailed decorative finishes will normally increase manufacturing costs.

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Access and scaffolding

Ground-floor windows with clear internal and external access are usually easier to replace.

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Costs may increase where installers need:

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• Scaffolding or access towers

• Specialist lifting equipment

• Additional labour

• Road or pavement permits

• Difficult delivery arrangements

• Protection over conservatories or extensions

• Access around fitted furniture or shutters

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Check whether scaffolding and access equipment are included in the quotation or will be charged separately.

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UPVC Replacement Window Costs

 

UPVC remains a popular choice because it is generally affordable, low-maintenance and available in a wide range of styles.

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The cost of UPVC replacement windows will depend on:

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• Frame size and profile

• Number of opening sections

• Casement, flush or sash design

• White, coloured or woodgrain finish

• Double or triple glazing

• Energy rating

• Locking system

• Trickle ventilation

• Installation access

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Current UK guides place standard fitted UPVC casement windows broadly between £500 and £1,250, although smaller and simpler units may be available for less.

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Flush casement frames, coloured finishes and UPVC sash windows will normally cost more than basic white projecting casements.

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UPVC products that look similar can contain different reinforcement, seals, locks and hardware. The specification should therefore be compared as carefully as the price.

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Timber Replacement Window Costs

 

Timber replacement windows generally cost more than standard UPVC because of the materials, manufacturing and finishing involved.

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Common choices include:

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• Engineered softwood

• Hardwood

• Oak

• Sapele

• Accoya and other modified timbers

• Traditional box sash windows

• Flush timber casements

• Bespoke heritage windows

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Timber is often selected for period homes, listed buildings and conservation areas where traditional proportions and materials are important.

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The higher initial price may be balanced by the ability to repair, redecorate and maintain the frames over a long service life. Factory-applied coatings can also reduce the amount of immediate maintenance required.

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Aluminium Replacement Window Costs

 

Aluminium replacement windows usually cost more than standard UPVC but offer slim frames, strength and a contemporary appearance.

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They are commonly used for:

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• Modern homes

• Extensions

• Large picture windows

• Wide glazed openings

• Contemporary bays

• Properties requiring narrow sightlines

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The cost will depend on the size of the frames, opening arrangement, glazing weight, thermal performance and powder-coated finish.

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Aluminium is particularly suitable for large windows because its strength allows narrower sections to support substantial areas of glass.

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Sash Window Replacement Costs

 

Sash windows are normally more expensive than standard casement windows because they contain additional frame sections and specialised sliding mechanisms.

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Costs are influenced by:

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• Timber or UPVC construction

• Traditional cords and weights

• Spring-balanced operation

• Standard or slim double glazing

• Georgian glazing bars

• Decorative sash horns

• Bespoke mouldings

• Draughtproofing

• Conservation or listed-building requirements

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Current price guides indicate approximately £600–£1,200 for UPVC sash replacements and around £1,000–£3,000 for timber sash windows, depending on size, specification and detailing.

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Before removing original timber sashes, it is worth checking whether they could be repaired, draughtproofed or combined with secondary glazing. Retaining the existing windows may be preferable where they contribute to the character of the property.

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Bay Window Replacement Costs

 

Bay windows usually cost more than flat windows because they contain several connected frames and may support part of the structure above.

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A bay-window replacement may involve:

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• Several individual window sections

• Reinforced corner posts

• New structural supports

• Temporary support during removal

• Replacement cills

• Insulation around the bay

• Roof or canopy repairs

• Internal boarding and plastering

• External trims and weatherproofing

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Current UK pricing indicates that a replacement bay may cost approximately £1,100–£4,000, with around £2,000 being a frequently quoted average for a conventional installation.

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The installer should establish whether the existing frames support masonry, floors or roofing before removal begins. Structural work should be identified separately within the quotation.

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Average Cost of Whole-House Window Replacement

 

The average cost of replacing windows throughout a home cannot be calculated accurately from the number of bedrooms alone.

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Two three-bedroom houses may contain very different windows. One could have eight simple casements, while another includes:

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• A large front bay

• Several sliding sash windows

• French or patio doors

• Bespoke timber frames

• Coloured aluminium windows

• Acoustic or security glazing

• Difficult upper-floor access

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

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Replacing several windows together may reduce the average cost per opening because surveying, manufacturing, delivery and installation can be organised as one project.

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Replacing the Glass Rather Than the Whole Window

 

Condensation or misting between the panes usually indicates that the sealed double glazed unit has failed.

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Where the surrounding frame remains sound, it may be possible to replace only the glass. Current guides place replacement double glazed units broadly between £55 and £300 per window, depending on size, glass type and access.

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Glass-only replacement may be suitable where:

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• The frame remains structurally sound

• The window opens and closes properly

• Hinges and locks remain serviceable

• There are no serious draughts

• The surrounding seals are in reasonable condition

• The frame still provides acceptable insulation

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Complete window replacement may offer better value where frames are distorted, rotten, insecure or no longer capable of supporting modern glazing.

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Repair or Replace?

 

Not every faulty window needs to be replaced.

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Repairs may be considered for:

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• Failed hinges

• Damaged handles

• Faulty locking mechanisms

• Perished seals

• Draughts around opening sections

• Broken sash cords

• Localised timber decay

• Misted sealed units

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Replacement may be more appropriate where several problems occur together or where the frames have reached the end of their practical life.

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An experienced installer should explain both options rather than recommending full replacement automatically.

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Additional Costs to Check

 

A replacement window quotation should state whether the following items are included:

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• Removal of the existing frames

• Disposal and recycling

• New internal and external cills

• Trims and sealants

• Plaster repairs

• Redecoration

• Scaffolding

• Safety glazing

• Trickle vents

• Structural support

• Building Regulations certification

• Parking or permit costs

• VAT

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Some companies include basic making good but exclude final decoration. Older properties can also reveal concealed defects once the existing frames have been removed.

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A modest contingency can help cover unexpected repairs to plaster, brickwork, timber or lintels.

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Comparing Replacement Window Quotes

 

Obtain itemised quotations based on the same frame and glazing requirements.

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Each quotation should identify:

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• Window dimensions

• Frame material and manufacturer

• Opening arrangement

• Glass specification

• Window energy rating or U-value

• Frame colour and finish

• Handles and locking systems

• Ventilation provision

• 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 install replacement windows” does not provide enough detail for a fair comparison.

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Be cautious about large headline discounts or offers that require an immediate decision. The final price and written specification are more important than the claimed saving.

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Planning Permission and Building Regulations

 

Windows of a similar appearance can often be replaced without planning permission in a house. Additional controls may apply to listed buildings, conservation areas, flats, maisonettes and properties affected by an Article 4 Direction. A new bay window can also be treated differently because it projects beyond the existing wall.

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Replacement windows are covered by Building Regulations. An installer registered with an authorised competent-person scheme can self-certify qualifying work and provide evidence of compliance. Where a registered installer is not used, a Building Regulations application may be required.

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Any planning and certification requirements should be confirmed before the windows are ordered.

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Getting an Accurate Replacement Window Cost

 

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

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The installer should inspect:

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• Each window opening

• Existing frames and cills

• Brickwork and lintels

• Bay-window supports

• Internal finishes

• External access

• Ventilation requirements

• Safety-glass locations

• Escape-window requirements

• Planning restrictions

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This allows the replacement windows to be properly specified and reduces the possibility of unexpected charges after work begins.

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Find Trusted Replacement Window Installers

 

Replacement window costs should be considered alongside frame quality, glazing performance, security and installation standards. Accurate measurement and careful fitting are essential to achieving secure, weatherproof and energy-efficient windows.

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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 replacing your windows.