Window replacement London: repair or replace, then compare quotes
Compare free written quotes from local installers who cover your London postcode, for replacement windows, glass-only units, sash repairs and secondary glazing. Many London jobs are repairs, not replacements: a misted unit, a broken lock or a sash that sticks.
29.2% of London homes were built before 1919, against 20.6% across England and Wales
- Repair prices too: say so on the confirmation call to confirm
- Sash, casement and bay windows surveyed and quoted in writing
- Free, no obligation: decline any quote you do not want
How it works
From one form to written London window quotes
Describe the windows
Property type, window count, frame material, timing, ownership and postcode.
Confirm on one call
On the call, mention sashes, repairs, a lease or a listed building. They pass the job to local installers who cover your postcode.
Compare after the survey
Each installer surveys every opening and quotes in writing. Compare them line by line.
What fitters quote for
Window jobs you can get quoted for in London
London window fitters quote for full replacement, glass-only units, repairs, sash overhauls and secondary glazing.
- Replacement windows: sash, casement and bay, in timber or uPVC.
- Glass-only sealed units for misted panes in sound frames.
- Repairs to stiff hinges, broken handles and locks.
- Sash overhauls: cords, beads and draught-proofing.
- Secondary glazing for listed or protected buildings.
Ask the installer whether a door can go on the same quote.
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Local factors
What changes a London window replacement quote
Five things change a London window replacement quote: the age of the home, flats, listed status, Article 4 streets and the energy standard. Check them before the survey, so the quotes compare line for line.
| In London | What it changes in your quote | Ask or check |
|---|---|---|
| 29.2% of homes built before 1919VOA, March 2026 | More sash and period windows | Refurbish, secondary glaze or replace |
| More than half of households in flatsCensus 2021 | Landlord consent, and often planning permission | The block's window specification |
| 19,286 listed building entriesHistoric England | Listed building consent for window changes | A secondary glazing option |
| 91 Article 4 recordsplanning.data.gov.uk | Planning permission on those streets | Who prepares the application |
| 1.4 W/m²K or WER band BApproved Document L | The minimum for each replacement window | The U-value or WER of each window |
Permission first
Window replacement quotes for London flats, listed homes and Article 4 streets
Three groups need permission before a London window replacement: leaseholders, owners of listed homes and owners on Article 4 streets. A house outside those groups usually needs no planning permission for windows of similar appearance (Planning Portal).
Leasehold flats
Flats have no householder permitted development rights, so a change of appearance can need planning permission. The Planning Portal adds that a leaseholder "may first need to get permission from your landlord or management company". Get written consent and the block's window specification before you book surveys. Our guide to replacing windows in a leasehold flat explains the licence for alterations.
Listed buildings
London has 19,286 listed building entries on the Historic England list. A listed home needs listed building consent for any window change that affects its character, inside or out.
Article 4 streets
The national planning dataset holds 91 London Article 4 records that remove the householder right to alter a house, or that name windows. Kensington and Chelsea, Hackney's De Beauvoir area and Islington all control window changes this way. Check your borough's conservation map. Borough-by-borough rules and the Heathrow and London City airport schemes are on our page for double glazing quotes in London.
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Period homes
Sash and period window replacement quotes in London
London's sash windows are refurbished when the box frame is sound, secondary glazed when the building is listed, and replaced when the frame has rotted. 29.2% of London homes were built before 1919 and 20.9% before 1900 (VOA, March 2026).
- Listed homes: Historic England says historic windows that add to significance "should be retained and repaired where possible", and replaced "with accurate copies" only when beyond repair.
- Character windows that cannot reach 1.4: Approved Document L accepts a centre pane U-value of 1.2 W/m²K, or single glazing with low-emissivity secondary glazing.
- Unlisted houses: timber or uPVC sash replacements, with the box sash or spring balance mechanism named on the quote.
Ask every installer to quote the same route, so the prices compare. Our page on sash window replacement covers new sashes in an old box, restoration and the eight items a sash quote must list.
Get sash and period window quotesFree, no obligation
Sign-off
Do replacement windows in London need Building Regulations approval?
Yes. A replacement window is a "controlled fitting" under the Building Regulations, so every whole-window replacement needs sign-off (Planning Portal). There are two routes:
- Competent person scheme: a FENSA, CERTASS or other registered installer self-certifies the work. GOV.UK lists six schemes for replacement windows: Blue Flame Certification, CERTASS, Certsure, FENSA, NAPIT and ASSURE.
- Building control: an unregistered fitter needs your borough's building control to approve the work, and you arrange it.
- Glass-only swaps: the Planning Portal page does not cover them, so ask whether a certificate applies to a unit-only job.
In England a replacement window must reach a U-value of 1.4 W/m²K or a Window Energy Rating of band B (Approved Document L). The new opening must give at least the same means of escape as the old one, which matters on upper floors of converted houses.
The job, step by step
What does window replacement in London involve?
Window replacement in London runs in six stages: consent, survey, written quote, contract, fitting and sign-off.
- Check consent. Flats, listed buildings and Article 4 streets need permission before an order.
- Book a survey of every opening. The installer measures each opening and checks sills, lintels and access. A salesperson's rough sizing is not the survey, and the price can change after a full technical survey.
- Get an itemised written quote. Each window is listed with its size, style, opening panes and glass.
- Agree a fitting date in writing. Off-premises contracts must state when the trader will perform the work (Consumer Contracts Regulations 2013, Schedule 2). Without a date, the law only requires "a reasonable time" (Consumer Rights Act 2015, s.52).
- Fit and make good. Plaster, reveals and sills are made good inside and out.
- Receive the certificate. A FENSA or CERTASS installer must give you a compliance certificate within 30 days of finishing (Building Regulations 2010, regulation 20).
Ask each installer who measures, who orders and who carries the cost of a wrong size.
The quote
What should a London window replacement quote include?
A London window replacement quote lists every window, the work around it, the paperwork and the payment terms. Lay three quotes side by side and check for these lines:
- Each window with size, style, opening panes and glazing bars
- Frame system by name, and the U-value or Window Energy Rating per window
- Removal and disposal of the old windows, and making good inside and out
- Access: scaffold or tower for upper floors, and who arranges parking for the van
- Who prepares drawings for the freeholder or a planning application
- FENSA, CERTASS or building control sign-off, and who pays for it
- Guarantee length, and whether it is insurance-backed
- Deposit, payment stages, fitting date, total price including VAT and the date the quote expires
Our guide on how to compare double glazing quotes shows how to line them up.
Get itemised London window quotesFree, no obligation
Repair or replace?
Repair or replace your London windows?
Repair the window when the frame is sound, and replace it when the frame has failed. Google's map results for "window replacement London" are all repair and sash firms.
| What you see | Usual fix | Ask the installer for |
|---|---|---|
| Mist or condensation between the panes | New sealed unit, frame kept | A glass-only price per window |
| Stiff hinge, broken handle, lock that will not catch | Hardware repair | A parts and labour price |
| Rattling or draughty sash in a sound box frame | Sash overhaul: cords, beads, draught-proofing | Refurbishment priced per window |
| Single glazing on a listed or protected building | Secondary glazing, original kept | A secondary glazing option |
| Rotten sill or box frame, warped or cracked uPVC | Full window replacement | The new window's U-value or energy rating |
Say on the confirmation call which windows only need repair, so installers quote repair, glass-only and full replacement side by side.
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Before you sign
How do you check a London window fitter?
Check a London window fitter on four things: scheme registration, company history, guarantee and how they found you.
- Search the company on the FENSA or CERTASS register itself, not the logo on its van.
- Look it up on Companies House for its age, name changes or a past liquidation.
- Ask for the insurance-backed guarantee provider by name, then confirm the cover with that provider.
- Refuse doorstep offers: London Trading Standards says officers "hear from hundreds of Londoners who are victims of criminals calling at their homes".
If you sign at home, you usually have at least 14 days to cancel, but made-to-measure windows can be an exception, so check the contract before you sign. See our guide to the double glazing cooling off period.
Areas this page covers
Areas of London this page covers
This page is about window replacement across Greater London's 32 boroughs and the City of London. Enter the property postcode in the form, and your enquiry goes to local installers who cover that postcode; we cannot promise cover for every street.
- Central: City of London, Westminster, Camden, Islington (EC, WC, W1, NW1, N1)
- North: Barnet, Enfield, Haringey (N, EN)
- East: Hackney, Tower Hamlets, Newham, Redbridge, Havering (E, IG, RM)
- South East: Southwark, Lewisham, Greenwich, Bromley, Bexley (SE, BR, DA)
- South West: Lambeth, Wandsworth, Croydon, Sutton, Kingston (SW, CR, SM, KT)
- West: Hammersmith and Fulham, Ealing, Harrow, Hillingdon, Hounslow, Richmond (W, HA, UB, TW)
Related guides
FAQ
Window replacement in London: common questions
Can I replace windows in a conservation area in London?
Yes, with matching windows, and with planning permission on Article 4 streets. Check your borough's conservation map before you order.
How do I find reliable window fitters?
Reliable window fitters appear on the FENSA or CERTASS register, have a Companies House record you can check, and give an itemised written quote with an insurance-backed guarantee.
What is a FENSA certificate, and why do I need one?
A FENSA certificate proves that a FENSA-registered installer has self-certified your replacement windows under the Building Regulations. Keep it with your property papers as the record of compliance.
How long does window replacement take?
Window replacement takes as long as the fitting date written into your contract, so agree that date before you sign. The certificate must reach you within 30 days of the work finishing.
Is it worth replacing 20 year old double glazing?
Replacing 20 year old double glazing is worth it when the frames are rotten, warped or no longer close tight. A misted unit in a sound frame needs only new glass.
What are the disadvantages of double glazing?
The main disadvantages of double glazing are sealed units that eventually mist, the upfront cost, and the loss of original windows on a period home. Historic England asks owners of listed homes to repair historic windows where possible.
Is double glazing glass replacement cheaper than a full window replacement?
Yes, Checkatrade's London cost guide puts glass-only replacement below a full window, because the frame stays in place. Ask for both prices on the same quote.
How much does window replacement cost in London?
Window replacement in London is priced per window after a survey, and our sister site sets out what window replacement costs per window.
Compare London window replacement quotes
Sort consent first, then let local installers survey and quote in writing. For the wider London picture, see double glazing quotes in London.
Get free quotes
Sources
- Valuation Office Agency, Council Tax stock of properties 2026, table CTSOP4.1, 31 March 2026
- Census 2021 TS044 Accommodation type, ONS via Nomis
- Planning Portal, doors and windows: planning permission and Building Regulations; change the windows of a flat
- Approved Document L, Volume 1 (2021 edition incorporating 2023 amendments), Table 4.2 and paragraph 4.10
- GOV.UK, competent person schemes (updated 17 September 2026)
- Building Regulations 2010, regulation 20
- Consumer Contracts Regulations 2013, Schedule 2 and regulation 28; Consumer Rights Act 2015, section 52
- Historic England, modifying historic windows
- planning.data.gov.uk, listed building and Article 4 direction datasets (flagged incomplete)
- Kensington and Chelsea, Article 4 directions; Hackney, De Beauvoir conservation area; Islington, conservation areas
- London Trading Standards, Don't deal at the door
- FENSA, fensa.org.uk; CERTASS, certass.co.uk; Companies House, company search
- Checkatrade, Window Fitters in London (glass-only vs full window)
- Google UK results for "window replacement london", checked 1 October 2026