Window & Door Installation Contracts: What to Include (UK 2026)

Most window and door jobs in the UK are still agreed on a quote and a handshake. That works right up until it does not — a customer remembers a different colour, a rotten lintel turns up on removal, or a deposit is disputed six weeks later. A contract is not about distrust. It is about both sides remembering the same job.

What a good installation contract covers

1. The parties and the site — who is contracting, and the address the work happens at. Include your company number if you have one.
2. The works — the products, finishes, sizes and accessories, tied to the specification and quote rather than described loosely.
3. Price and payment — the total, whether it includes VAT, what deposit is due and when the balance falls.
4. Timing — start and duration as honest estimates, with a note that manufacturer delays and unsafe weather are outside your control.
5. Variations — that any change to scope, price or timescale is agreed in writing before the varied work happens.
6. Access and site conditions — what you need from the customer, and what you will protect, remove and leave clean.
7. Guarantees — your workmanship period, and that manufacturer guarantees pass through on their own terms.
8. Insurance — that you hold public liability cover and will evidence it on request.

The clause installers most often get wrong

Work found necessary but not quoted. Rotten timber, a failed lintel, plasterwork that disintegrates when the old frame comes out — none of it is visible at survey, and all of it costs money. If the contract does not say what happens, you are choosing between absorbing it and having an argument on site.

The workable version: the price covers the listed specification only, and anything else is quoted separately and carried out only with the customer’s written agreement. It protects the customer from surprise bills as much as it protects you, which is why it rarely gets pushed back on.

Cancellation rights when you sign in someone’s home

This is the part that catches people out. If the contract is concluded at the customer’s home, at their workplace, or at a distance — rather than at your own premises — it is an off-premises or distance contract under the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013. The customer gets a statutory right to cancel, and you have obligations that go beyond simply mentioning it.

• You must give the customer prescribed information about the right to cancel, on a durable medium, including a cancellation form they can use.
• If you do not, the cancellation period can extend well beyond the usual fourteen days.
• If the customer wants work to start inside the cancellation period, they need to ask for that expressly — and you need a record of it before you order anything.
• Goods made to the customer’s specification are treated differently from off-the-shelf goods, which matters a great deal in an industry where almost everything is made to measure.

Door-to-door and door-drop leads land squarely in this territory, because the signature usually happens at the kitchen table. If you are running any kind of local canvassing, this is the area worth paying a solicitor to look at once, properly.

Statutory rights sit on top, always

Nothing in your terms displaces the Consumer Rights Act 2015 — work must be carried out with reasonable care and skill, and goods must be as described and of satisfactory quality. A clause attempting to exclude that is not merely unenforceable, it makes the whole document look like it was written to catch someone out. Replacement windows and doors are also notifiable under the Building Regulations in England and Wales, so say plainly whether you are self-certifying under a competent person scheme or whether building control is involved, and who is responsible.

Make it easy to sign

A contract that lives as an email attachment gets printed, lost, and signed a fortnight late. Put it where the customer already is — in the same document as the renders and the quote they have been looking at — and let them sign it there. Momentum matters: the best moment to get agreement is while they are still excited about the pictures.