To get good window installation quotes, give every installer the same detailed brief, ask for at least three written quotes, and compare them line by line rather than by the bottom-line figure. Check that each installer is registered to certify the work, and that each quote covers the same windows, the same specification and the same extras. This guide shows you how, with a checklist you can copy.
TL;DR
- Get at least three written quotes, as Citizens Advice recommends, so you can judge whether a price is fair.
- Send every installer identical information: window count, sizes, frame material, glass, colour and opening style.
- A cheap quote can leave out disposal, making good or scaffolding, or recover the cost later through extras. Compare the scope, not just the total.
- Use an installer registered with a competent person scheme such as FENSA, so the work is certified and the warranty insurance is in place.
- Check the cancellation terms before you sign. You may have 14 days to change your mind.
Table of Contents
- What a window installation quote should tell you
- What to tell installers so the quotes match
- How to compare quotes like for like
- Credentials and regulations to check before you accept
- Extra costs and terms to check before you sign
- Is the price fair?
- Doors and conservatories: what changes
- Why we built Compare Glazing Quotes
- Get your quotes in three steps
- A short checklist to take away
- FAQ
- Sources
What a window installation quote should tell you
A quote is a price for a defined job. If the job is vague, the price means little and you cannot compare it with anyone else's. A useful quote for replacement windows should set out:
- Each opening: a schedule listing every window by room or position, with its size and opening style (fixed, side-hung casement, tilt and turn, sash).
- The product: frame material (uPVC, aluminium, timber), the make or range, the glazing (double or triple), the glass type, the colour inside and out, and the handles and trims.
- The installation scope: whether old frames are removed, whether new cills are fitted, and how the gaps around the frame are sealed and finished.
- Removal and disposal: whether the old windows and rubbish are taken away, and whether that is included in the price.
- Making good: what happens to plaster, decoration and external finishes after the frames go in.
- The total price and VAT: the figure you will actually pay, stated clearly as including or excluding VAT.
- Payment terms: the deposit, the stage payments and the final balance, and when each is due.
- Timescales: the lead time for manufacture and how long the fitting takes.
- Exclusions: anything not covered, such as scaffolding, internal decoration or work on a conservatory roof.
- Guarantees and certification: the length and cover of the product and installation guarantees, and how the work will be certified.
If any of these is missing, ask for it in writing before you compare prices. A quote that says only "supply and fit 8 windows, one price" gives you nothing to hold anyone to.
What to tell installers so the quotes match
The single biggest reason quotes differ is that installers were quoting for different things. One visited, measured and assumed white uPVC. Another was told nothing and priced a mid-range casement. You fix this by giving everyone the same brief.
Before you ask, gather this:
- Number of windows, and which rooms they are in.
- Approximate sizes, or ask for a free survey so the installer measures properly. Measure only to give a rough idea, never to order.
- Property type and age, and whether it is a flat, a house, or a listed building or in a conservation area. Tell installers if either applies, because it can limit what you are allowed to fit.
- Frame material and colour, including whether you want a different colour inside and out.
- Opening style, particularly if a window is an escape route from a bedroom and needs to open wide enough.
- Glazing preferences, such as double or triple glazing, or noise reduction if you live on a busy road.
- Extras you want, such as new cills, trickle vents, child locks or window boards.
- Your timing, whether you are flexible or have a deadline.
- Access, for example upper floors, narrow side passages or a need for scaffolding.
Write it down once and send the same text to each company. That gives you the closest thing to a like-for-like comparison before anyone visits.
How to compare quotes like for like
Lay the quotes side by side and work through them in this order.
Start with the specification, then the price
Check that every quote lists the same number of windows, the same frame material, the same glazing and the same opening styles. If one quote names the product range and another says only "white uPVC windows", ask the second installer which range they mean. A lower price may simply reflect a thinner frame, a basic glass specification or fewer opening sashes.
Look for what is missing
FENSA's guidance on appointing an installer points out that a low quote may leave out items such as disposal, making good or scaffolding, or try to recover costs through extras. It also notes the cheapest quote is not always the best value. So tick off each cost against every quote. Where one installer has included scaffolding and another has not, ask for a price for it from the second before you decide.
Compare terms as well as costs
Some installers ask for a large deposit up front. Others take stage payments. Compare how much you would have paid before a single frame is delivered, and how long you wait between ordering and fitting. A quote with a slightly higher price and a small deposit may suit you better than the cheapest with a big payment at the start.
Use a simple scorecard
| Check | Installer A | Installer B | Installer C |
|---|---|---|---|
| Same number of windows and sizes | |||
| Same frame, glass and colour | |||
| Removal and disposal included | |||
| Making good included | |||
| Scaffolding included or priced | |||
| VAT shown clearly | |||
| Deposit and payment stages | |||
| Lead time and fitting time | |||
| Guarantee length and what it covers | |||
| Certification route stated |
A blank box is a question to put to the installer, not a reason to guess.
Credentials and regulations to check before you accept
Replacing windows in England is building work, and it has to comply with the Building Regulations. The government's guidance explains that a registered installer handles compliance for you, so you do not need to contact a building control body. Otherwise you must apply for approval and pay for an inspection yourself.
The same guidance warns that if work has not been notified or certified, the local authority may have no record that it complies, and you may be asked for certificates when you sell the home. Ask for the certificate once the job is finished and keep it with your property papers.
Three things are worth checking on every quote:
- Registration with a competent person scheme. FENSA is the best known for windows and doors. Ask for the installer's registration number and say you want the certificate issued at the end.
- Warranty insurance. FENSA says its registered installers are obliged to provide insurance-backed cover for the installation if the company stops trading during the warranty period. Ask what the guarantee covers and for how long, and get it in writing.
- Trade body or trust-mark membership. For energy efficiency work, Citizens Advice suggests checking installers against registers such as TrustMark, Buy with Confidence or Which? Trusted Trader.
Note that the rules above are written for England. If you live in Wales, Scotland or Northern Ireland, ask your local building control or the installer how certification works where you live.
Extra costs and terms to check before you sign
VAT
Work out whether the price you are comparing includes VAT. Some quotes show the figure before VAT, which makes them look cheaper than one that includes it. Ask every installer to state the total you will pay, and check the current rules on GOV.UK's VAT pages if you think any reduced rate might apply to your job.
Cancellation rights
Citizens Advice explains that you might be able to cancel within 14 days of telling the trader you want them to do the work, or of signing a written contract. Read the contract for how to cancel and what happens to your deposit. Be careful if an installer asks you to start work inside that period, and ask what you would owe if you cancelled.
Payment and deposit
Agree payment stages in writing, tied to clear points such as delivery of the windows and completion of fitting. Pay the final balance only after you have checked the work and received your certificate.
Variations
Ask what happens if the installer finds rot in a frame, a lintel problem or an unusual opening on the day. A good quote explains how extra work will be priced and agreed before it is done.
Is the price fair?
No single figure fits every home. Cost depends on the number of windows, their size, the frame material, the glass, the opening styles and the access to your house. A flat with four standard windows and a large house with bespoke sizes are completely different jobs, and a published national average will not tell you which end of the range yours falls in.
That is why Citizens Advice recommends getting at least three written quotes. With three comparable prices for the same specification, you can see which is high, which is low and which looks about right. If one is far below the others, look hard for what has been left out. If one is far above, ask why: it may include a higher-grade product or an extra the others did not price.
Doors and conservatories: what changes
The same discipline applies to new doors and conservatory work, with a few extra points.
Doors. Say whether you want a front, back, patio or French door, the material, the security specification and the colour. Ask whether the price includes the frame, the lock and handles, the threshold and the finishing around the frame. Ask who certifies the work.
Conservatories. These are bigger projects, so a written specification matters even more. Ask each installer to detail the base and foundations, the frame and glass, the roof type, electrics and heating if you want them, and who handles any approvals the project needs. Ask them to confirm in writing whether planning permission or Building Regulations approval applies to your design, and who applies for it. Check the programme: how many weeks from order to completion, and what you should expect to be disrupted at home.
In both cases, use the scorecard above and add a line for each extra the project involves.
Why we built Compare Glazing Quotes
We started this service because we saw homeowners spend weeks phoning around, repeating the same details and ending up with quotes that could not be compared. Each installer described the job differently, so the prices told them very little.
Our approach is to take the details once. You tell us what you need, we match you with local installers, and you compare their quotes side by side. We only include installers who are certified with FENSA and/or CERTASS, because we believe a quote is only worth comparing if the work can be properly certified at the end.
The service is completely free for homeowners and carries no obligation. We say it can help you save up to £2,000, because seeing several quotes for the same job shows you what the market price really looks like. You stay in control and you choose who, if anyone, you want to work with.
James
Get your quotes in three steps
If you would rather not contact installers one by one, our free comparison service does the legwork. You tell us about your windows, doors or conservatory, we match you with local installers, and you compare the quotes they send. It costs you nothing and you are under no obligation to accept any of them.
Use the checklist in this guide when the quotes arrive. Because every installer starts from the same details, the quotes are easier to set against each other, and you can spend your time on the questions that matter: what is included, how it is certified and what is guaranteed. You can start at Compare Glazing Quotes.
A short checklist to take away
Before you accept any quote, tick off each of these:
- I have at least three written quotes for the same specification.
- Each quote lists every window or door, with sizes and opening styles.
- Frame material, glass and colour are named, not implied.
- Removal, disposal and making good are included or priced.
- Scaffolding is included or priced if I need it.
- VAT is shown, and the total is the amount I will pay.
- The deposit and stage payments are written down.
- The lead time and fitting time are stated.
- The installer is registered with a competent person scheme and will issue a certificate.
- The guarantee and warranty insurance are explained in writing.
- I know my cancellation rights and how to use them.
FAQ
How many window quotes should I get?
Aim for at least three written quotes. Citizens Advice recommends this because it helps you judge whether a price is fair. Give each installer the same brief so the quotes can be compared properly.
Should I always choose the cheapest quote?
Not automatically. FENSA notes that the cheapest quote is not always the best value, and that a low price can leave out items like disposal or scaffolding. Compare what each quote includes, its guarantees and its certification before you decide on price.
Do I need a FENSA certificate?
Replacement windows have to comply with the Building Regulations. If you use a registered installer, they deal with compliance and issue the certificate. If you do not, you must apply for approval and pay for an inspection, and you may be asked for certificates when you sell your home.
Can I cancel after signing a contract for new windows?
You might be able to. Citizens Advice says you may have 14 days to cancel from telling the trader you want them to do the work, or from signing a written contract. Check the contract wording and ask the installer in writing how cancellation and your deposit work.