Three window quotes: £3,200, £4,900 and £6,100. Same house, same windows. Which is really cheapest? The honest answer is that you cannot tell until the window replacement quotes describe the same job. This guide shows how to compare window quotes by specification, certificate, access and guarantee, not by headline price.
What Should a Window Replacement Quote Include?
A window replacement quote should include each window’s size and style, frame material, glazing specification and energy rating, installation and old window removal, a Building Regulations certificate, scaffolding or access, finishing, disposal, guarantee, VAT and payment terms. Use this window quote checklist:
| Item | What to look for | Why it matters |
|---|---|---|
| Windows | Size, style and number of each | Stops “per window” confusion |
| Frame and glass | Material, glazing, energy rating | Changes performance and price |
| Certificate | Scheme or building control sign-off | Needed when you sell |
| Access | Scaffolding included or not | A common hidden extra |
| Finishing | Cavity closers, sills, trims, make good | Often left out |
| Disposal | Old windows removed | Can be an extra charge |
| Guarantee | Length, cover, who backs it | Not all guarantees are equal |
| VAT and payment | VAT basis, deposit, stages | Affects the real total |
Why Window Replacement Quotes Vary So Much
Why are window quotes so different? Installers choose different frame materials, glass, energy ratings and finishing, and some include scaffolding while others do not. Guarantees, certificates and VAT also differ. A double glazing quote too cheap to match the rest may simply leave items out. See builder quote much cheaper than the others?.
Per Window vs Total Price: Do Not Compare the Wrong Number
A “per window” price and a “total” price are not the same measure. Ask whether the per-window figure includes fitting, certificate, disposal, trims and VAT, and whether the total covers every window you listed. Put every quote on the same basis first.
Is FENSA Included in a Window Quote?
Not always, and FENSA is not the only route. For replacement windows, Building Regulations normally apply, and the Planning Portal says a registered competent person scheme installer can self-certify without a building control application. On the GOV.UK list of authorised schemes for existing homes, FENSA appears alongside Certass, NAPIT, Assure, Blue Flame Certification and Certsure. Write “FENSA or another competent person scheme” and confirm the installer’s registration with the scheme itself.
The certificate matters because a buyer’s solicitor may ask for it when you sell. Ask who provides it, and when.
Is Scaffolding Included in a Window Replacement Quote?
Not necessarily. Upper-floor windows may need scaffolding or other access, and some quotes include it while others add it later. Ask each installer to state it in writing as included, excluded or priced separately.
Worked Example: Two Window Quotes for the Same House
Figures are illustrative only, not UK market prices.
| Item | Quote A (£4,900) | Quote B (£3,200) |
|---|---|---|
| Energy rating | A-rated, stated | Not stated |
| Certificate | Competent person scheme | Not mentioned |
| Scaffolding | Included | Not mentioned |
| Cavity closers, make good | Included | Excluded |
| Disposal | Included | Excluded |
| Guarantee | Insurance-backed, stated | Unclear |
Quote B is cheaper on paper, but it leaves several items open. Ask Installer B to confirm and price each in writing before comparing. Neither quote wins automatically.
Planning Permission and Building Regulations
For houses, like-for-like replacement windows usually do not need planning permission, but listed buildings, conservation areas and flats can differ, so check with your local authority. The Planning Portal notes that flats and maisonettes may need permission. Rules in Scotland, Wales and Northern Ireland differ.
Red Flags in a Window Quote
- Verbal quote only, or no survey
- A vague specification
- A large deposit with no stages
- No scheme registration or insurance proof
- “Today only” discounts
Questions to Ask Every Window Installer
- Is the price per window or total, and what does it include?
- What frame, glass and energy rating are quoted?
- Which scheme are you registered with, and who issues the certificate?
- Is scaffolding included?
- Are cavity closers, sills, trims and make good included?
- Is disposal included?
- What guarantee do you give, and who backs it?
- Is VAT included, and what deposit and stages apply?
For deposits, see how much deposit a builder should ask for. For wording, read quote or estimate and how to compare builder quotes.
How ScopeCheck Helps You Compare Window Quotes
ScopeCheck is a tool that compares UK home improvement quotes. Upload 2–5 quotes for the same job as PDFs, photos or text, and the report shows what each includes, what is missing and what to ask, with VAT shown on the same basis. Compare the quotes you already have: try a free preview of 2 quotes, see an example report or read how it works. ScopeCheck is provided by Dashient Ltd. AI-assisted analysis can contain errors, so check the original wording.
FAQs
Is FENSA included in a window quote?
Not always. Ask which competent person scheme the installer uses and who provides the certificate.
Is scaffolding included in a window replacement quote?
Not necessarily. Ask for it in writing as included, excluded or priced separately.
How many window quotes should I get?
Three is a common starting point, provided each covers the same specification.
Why are window quotes so different?
Specification, energy rating, finishing, access, guarantee and VAT often differ between quotes.
Do I need planning permission to replace windows?
Often not for like-for-like replacements in houses, but listed buildings, conservation areas and flats differ. Check locally.