HOW TO HIRE · TRADES & CONSTRUCTION

How to hire a window installer in the UK
The checks, the questions and the paperwork.

Replacing windows needs approval in England unless a FENSA or CERTASS installer self-certifies it. The check, the questions, and the certificate you need to sell.

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THE 60-SECOND VERSION

Hiring a window installer in five steps

  1. Check the schemeSearch the installer on FENSA or CERTASS — or another authorised scheme — before you sign.
  2. Get windows specifiedFrame material, glazing, opening style and colour for each window.
  3. Ask about fitting and finishingHow the frames are fixed and sealed, and how the reveals are made good.
  4. Read the cancellation termsMade-to-measure windows are usually outside the 14-day right; check before signing.
  5. Keep the certificateThe scheme certificate shows the windows meet the Building Regulations.

BEFORE YOU BOOK

Check before you book

FENSA or CERTASS

gov.uk says replacing windows and doors needs building regulations approval in England; installers on authorised competent person schemes — FENSA and CERTASS among them, with Blue Flame, Certsure, NAPIT and ASSURE also listed — self-certify the window replacement instead.

Check the installer on the scheme's own search before you sign. fensa.org.uk →

Scheme certificate

After a self-certified window replacement the scheme issues a certificate showing the work meets the Building Regulations; gov.uk's homeowner guide says to contact the scheme if it has not arrived within 30 days.

Ask when the certificate for the window replacement will arrive, and file it with the deeds. gov.uk →

Building warrant (Scotland)

If you live in Scotland and the window replacement needs a warrant, getting it is your job as owner — the council can fine you and have unwarranted work removed. In Northern Ireland, notify the council's building control ahead of the window replacement.

Scottish owners: see the warrant before work on the window replacement starts. In Northern Ireland, get the building control reference. mygov.scot →

Insurance and trader status

Public liability cover protects you if the window replacement damages your home or someone is hurt; ask for the insurer and limit. Dealing with a trader gives you the Consumer Rights Act 2015, and booking the window replacement at home or online normally gives 14 days to cancel under the Consumer Contracts Regulations 2013 — minus the value of anything you asked to be done in that time, and excluding goods made to order for you.

See the insurance certificate before you confirm the window replacement; the Locufy profile shows the trader and ID-checked badges.

VAT

Replacement windows and double glazing are standard-rated at 20% — HMRC lists glazing among the energy-efficient products outside the energy-saving relief, and its 5% grant-funded rate is only for listed heating appliances installed under a qualifying grant for someone aged 60 or over or on certain benefits — and a firm turning over more than £90,000 must charge the VAT and show it on its own line.

Ask for the VAT number, and look for VAT as its own line on the window quote. gov.uk →

“Which scheme are you on for the window replacement?”

A good answer: FENSA, CERTASS or another authorised scheme, with an entry you can find yourself.

“What glazing will the new windows have?”

A good answer: The unit specification stated per window, with safety glass where it is needed.

“How will the windows be fixed and sealed?”

A good answer: Frames fixed into the opening and sealed inside and out, with how the reveals are made good.

“Will escape windows be kept where they are needed?”

A good answer: Upstairs rooms that need an escape window keep one, with the opening size checked.

“What happens if a window opening is a different size?”

A good answer: Survey measurements taken by the window installer, not from your sketch.

“What guarantee covers the windows?”

A good answer: Frame, glazing and workmanship guarantees, each written down, and who backs them.

“Can I cancel after signing?”

A good answer: An honest answer: windows made to measure are usually outside the 14-day right, so the terms matter.

Getting the quote right

  • Each window by size, frame material, opening style and glazing
  • Removal of old frames and making good
  • Scheme certificate included
  • Deposit and when the balance is due
  • Who actually attends — the surveyor and the fitters, employed or subcontracted — and the business's VAT number, with VAT at 20% shown as its own line
  • The guarantees

Walk away if

  • Not on any authorised scheme
  • Huge discount for signing today
  • Large deposit for made-to-measure windows with no written terms
  • Measures from your sketch instead of surveying
  • No mention of the certificate
LOW
£350
TYPICAL
£750
HIGH
£1,500

What a window installer costs: £350–£1,500 per window

Windows are priced per window, by frame material, size, style and glazing; the number replaced at once brings the price per window down. Window & Double Glazing Installer price guide →

Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.

KNOW WHAT TO LOOK FOR? NOW FIND ONE

Window installers near you, with the badges that matter shown

ID checked, trader status and one score from every review — on the card, before you message anyone. Nearest first. No account needed to look.

Or post the job free and let them come to you.

  1. SurveyEach opening measured and the order confirmed in writing.
  2. ManufactureWindows made to the survey sizes.
  3. RemoveOld frames taken out with care to the reveals.
  4. Fit and sealNew frames fixed, packed and sealed inside and out.
  5. Finish and certifyReveals made good, windows adjusted, scheme notified and certificate issued.

Sealed unit
The double or triple glazed panel within the frame.
Casement
A window hinged at the side or top.
Sash
A sliding window, traditionally vertical.
Reveal
The side of the opening around the frame.
Escape window
An upstairs window big enough to get out of in a fire.
Scheme certificate
The certificate confirming the windows meet the Building Regulations.

AFTER

When the job is done

Keep the scheme certificateA buyer's solicitor asks for it for windows replaced since the rules came in.
Check every windowOpens, closes, locks, no draughts and no gaps around the frame.
File the guaranteesFrame, glazing and workmanship.
Write the reviewOnly booked jobs can be reviewed on Locufy, so yours carries weight; if the window replacement falls short, use the make-it-right step first and the provider is asked to fix it before the review is published.

STEP 1Start with the installer, in writingSend the installer a short, dated account of the problem with the window replacement and the fix you want. Section 49 of the Consumer Rights Act 2015 implies reasonable care and skill into the contract, and section 54 gives you repeat performance or a price reduction when it is missing.
STEP 2Use Locufy's make-it-right stepRate the window replacement under four stars and you are asked whether to send it to the provider first; we follow it through. Then the review goes up.
STEP 3Unapproved or dangerous workThe council is the authority for unapproved building work: tell building control in England, Wales or Northern Ireland if the window replacement went ahead without approval, or the building standards service in Scotland, where the owner carries the warrant duty. For a dispute about the window replacement with the trader, Trading Standards is reached through the Citizens Advice consumer helpline on 0808 223 1133 in England and Wales, Advice Direct Scotland on 0808 800 9060, or Consumerline on 0300 123 6262 in Northern Ireland.
STEP 4Money still in disputeIf the window replacement is still not settled, you can claim without a solicitor: the small claims track takes claims up to £10,000 in England and Wales, simple procedure up to £5,000 in Scotland, and the small claims court up to £5,000 in Northern Ireland.

Hiring a window installer: questions people ask

Not by law, but in England replacement windows need building regulations approval unless the installer self-certifies through an authorised scheme such as FENSA or CERTASS.

A certificate from the installer's scheme confirming the work meets the Building Regulations; contact the scheme if it has not arrived within 30 days.

£350–£1,500 a window, typically around £750. Frame material is the main driver, then size, style and how many you replace. How the figure is built up is in the Window & Double Glazing Installer price guide; search by postcode above to see what window installers near you quote.

Windows made to your specification are generally outside the 14-day cancellation right under regulation 28 of the Consumer Contracts Regulations 2013; check the terms.

Different building rules apply: in Scotland ask the council's building standards service, and in Northern Ireland the council's building control.

Ask the scheme the installer used; they can usually reissue it.

MORE GUIDES

More hiring guides in trades & construction

How to hire: Door InstallerHow to hire: Conservatory InstallerHow to hire: Orangery BuilderHow to hire: BuilderHow to hire: Carpenter & JoinerHow to hire: Garage Door InstallerHow to hire: RenderingHow to hire: CladdingAll 701 hiring guides →

Window installers near you

Window installers in LondonWindow installers in ManchesterWindow installers in BirminghamWindow installers in GlasgowWindow installers in BelfastAll window installers on Locufy →

Sources — checked October 2026

  1. FENSA — replacement windows and doors
  2. CERTASS — competent person scheme for windows and doors
  3. gov.uk — competent person schemes: current schemes and the work they cover
  4. gov.uk — building work, replacements and repairs to your home (England)
  5. gov.uk — building regulations approval (England)
  6. mygov.scot — if a builder is doing the work for you
  7. nidirect — how to apply for Building Regulations approval
  8. Consumer Rights Act 2015, section 49 — reasonable care and skill
  9. Consumer Rights Act 2015, section 54 — what you can ask for when a service falls short
  10. Consumer Contracts Regulations 2013, regulation 30 — the 14-day cancellation period
  11. Consumer Contracts Regulations 2013, regulation 28 — contracts the cancellation right does not cover
  12. Consumer Contracts Regulations 2013, regulation 36 — services started within the cancellation period
  13. Civil Procedure Rules Part 26 — the small claims track limit (England and Wales)
  14. Scottish Courts and Tribunals — making a claim under simple procedure
  15. nidirect — the small claims process (Northern Ireland)
  16. Energy-saving materials and heating equipment (VAT Notice 708/6) — 2.23 Other energy-efficient products (standard-rated); 3 Grant-funded heating (5%)
  17. GOV.UK — VAT rates
  18. GOV.UK — Register for VAT: when to register