Secondary glazing prices in the UK vary because each system is designed around the existing window. The number and size of openings, opening style, glass, frame, reveal depth, repairs, access, location and installation scope all affect a quotation.
As an early budgeting guide, standard professionally fitted secondary glazing is often discussed around £300–£800 per window, acoustic specifications around £600–£1,200, and heritage or unusually complex work around £1,000–£2,200. These are indicative ranges only, not offers or guarantees.
This guide keeps the focus on a national system-by-system comparison. For London-specific context, see the honest London cost comparison.
Indicative secondary-glazing costs by system
| System type | Indicative cost per window | What moves the price |
|---|---|---|
| Fixed | £250–£450 | Size, glass, finish, access and reveal preparation |
| Lift-out | £300–£600 | Panel size, safe handling, storage and refitting details |
| Hinged | £350–£700 | Hinges, catches, restrictors and clearance for operation |
| Horizontal or vertical slider | £450–£900 | Tracks, hardware, sash proportions, glass and installation |
| Acoustic specification | £600–£1,200 | Acoustic laminate, cavity, seals and survey requirements |
| Heritage or complex | £1,000–£2,200 | Large, curved, arched, listed or unusually detailed openings |
These are indicative 2026 planning figures. They may exclude repairs, decoration, access equipment, consent advice, VAT or making good. Ask each supplier to state inclusions and exclusions.
What changes the price?
Window size, number and opening style
A small fixed panel is not priced like a tall sash slider or a wide bay. A multi-window project may improve manufacturing efficiency, but it may also involve different opening styles and more surveying. A quotation should list each opening rather than multiplying one assumed rate.
Glass, frame and original-window condition
Standard glass may suit an additional thermal layer. Low-emissivity glass can be considered for thermal performance, while acoustic laminated glass may be considered where traffic noise is the priority. Secondary glazing does not repair rotten timber, failed putty, loose masonry, water ingress or broken sash cords, so keep any recommended repair or draught-proofing separate in the quote.
Access, location and making good
Parking restrictions, upper-floor access, narrow stairs, shutters, curtains, furniture and uneven reveals can change labour and logistics. London and other high-cost areas may benchmark higher, but there is no fixed national surcharge. Redecoration, plaster repairs and disposal should be stated explicitly.
Sash-window pricing
A straightforward sash opening may be discussed around £450–£900 per window, while larger, acoustic, heritage-detailed or repair-heavy openings may sit around £1,000–£2,200. These are indicative ranges, not a sash-window price list. Meeting rails, shutters, pulley access, glazing bars, reveal depth, opening method, glass and finish all need to be surveyed.
If a sash is beyond economic repair, replacement may be considered. A broad £2,000–£4,000 per replacement window comparison is sometimes used for specialist or heritage work, but it is equally indicative and can change with joinery, glazing, consent, access and decoration.
UK and London benchmarks
Published cost guides and quote-market references such as MyJobQuote and Checkatrade can provide orientation, but prices and methodologies change. An indicative UK benchmark of around £375 per window and an indicative London benchmark of around £490 per window may be useful in an early comparison. They are not current tariffs or promises of what a project will cost; check publication date, window type, VAT treatment and inclusions.
London quotations may reflect labour, parking, access, demand and property complexity. A rural project may involve travel or limited installer availability. Request like-for-like specifications from more than one supplier where practical.
Secondary glazing versus replacement windows
Replacement windows can be discussed around £2,000–£4,000 per window in a specialist or heritage comparison, while a straightforward secondary system may be around £300–£800. A possible 15% or £250–£400 saving is sometimes used in early comparisons when secondary glazing is set against a particular replacement quote. These are indicative comparisons only: exact windows, repairs, access, glass, frame, labour, disposal, making good, VAT and consent can change both figures.
Secondary glazing keeps the primary window in place and adds another layer to operate and maintain. Replacement provides a new integrated window but changes or removes original fabric and may have a different planning position. A measured survey should test both options against the building.
Thermal performance and energy figures
A U-value describes heat transfer through a defined construction. An illustrative secondary-glazing example might use a U-value around 0.65 W/m²K for a specified build-up, but that number cannot be transferred to every frame or glass combination. Ask whether a quoted U-value covers the glass, complete window or a modelled assembly.
Secondary glazing may reduce heat transfer and make a room feel less cold. It does not guarantee a bill reduction, EPC band or payback period. Heating controls, exposure, ventilation, occupancy, walls, roof, floors, doors, window condition and energy prices all influence the whole-home result. The condensation and comfort guide covers the practical context.
Planning and listed-building considerations
An internal system may leave the external elevation unchanged, but planning permission and Listed Building Consent are separate questions. Listed status, fixings, historic fabric, shutters, conservation-area policy, Article 4 Directions and local interpretation can affect the answer. Planning statements are case-dependent and subject to the current rules.
Historic England’s secondary-glazing guidance is useful background, not permission for a particular project. Send photographs, drawings and the specification to the relevant authority before ordering where consent may be relevant. Tenants and leaseholders should check their own approvals.
Questions to ask an installer
- What system, glass, frame, seals and air gap are proposed for each opening?
- Which repairs, draught-proofing, preparation and making-good items are included?
- Does the price include survey, manufacture, delivery, fitting, access, disposal and VAT?
- How will ventilation, cleaning, shutters, curtains, handles and escape access work?
- What warranty, maintenance advice and aftercare apply to the exact specification?
- Which planning, listed-building, conservation, landlord or freeholder approvals should be checked?
If a supplier quotes one rate per window without inspecting the property, treat it as an early estimate. An accurate comparison requires the same window count, dimensions, glass, opening style, finish and installation scope.
FAQs
How much does standard secondary glazing cost in the UK?
An indicative planning range is around £300–£800 per window for standard professionally fitted work. Size, opening style, glass, frame, repairs, access and installation scope can move the final quotation.
What does secondary glazing cost for sash windows?
A straightforward sash opening may be discussed around £450–£900, with larger, acoustic or heritage-detailed work around £1,000–£2,200. These are indicative ranges only.
Is secondary glazing cheaper than replacement windows?
It may be in a particular like-for-like comparison, but there is no universal percentage. Compare repairs, access, glass, disposal, making good, VAT and consent as well as the window price.
Does secondary glazing need planning permission?
The answer is property- and proposal-specific. Internal work may avoid some external-change issues, but listed buildings, conservation areas, Article 4 Directions, fixings and historic fabric can change the position. Check before commissioning.
Make the next step a measured one
Published costs are indicative starting points. A room-by-room survey can record condition, access, glass, air gap, opening style, heritage requirements and the scope of repairs before you compare quotations.
At SecondaryDoubleGlazing, we can help you compare the options without treating one number as a guarantee. Request a quote or call 020 7060 1572 to discuss your windows.