5 red flags to check in a builder's quotation

Most builders want to price a job fairly and do it well. But a quotation is the document that sets out what you are actually buying, and small gaps in it tend to become arguments later. None of the points below automatically means a builder is unreliable. They are prompts to slow down, ask questions and get answers in writing before you agree anything.

Every project is different, so treat this as a practical checklist rather than a set of rules.

1. The description of work is vague

A single line such as “build single-storey rear extension as per drawings” can hide a great deal. Which drawings, and which revision? Does it include the foundations the engineer has specified, or a standard assumption? Is the kitchen fitting included, or only the shell? When the scope is loose, the builder has to make assumptions — and you will not know what they assumed until something is missing.

A better quotation breaks the work into sections — groundworks, structure, roof, windows and doors, first fix, plastering, second fix, finishes, externals — so you can see what is priced and where the money sits.

2. There are no exclusions, or the exclusions are surprising

Every quotation excludes something. Good ones say so clearly. If there is no exclusions list at all, ask for one. If there is, read it carefully: items like skip hire, scaffold, building control fees, party wall matters, removal of spoil, making good of decorations, or connection to drainage can be significant.

Exclusions are not wrong in themselves. The problem is discovering them after you have compared prices, when a cheaper quote turns out to be cheaper because it leaves more out.

3. A large share of the price is provisional sums or allowances

Provisional sums and prime cost allowances are used where the detail is not yet known — a kitchen not yet chosen, or ground conditions not yet investigated. They are normal. But if a large part of the total sits in allowances, the quoted figure is really an estimate, and the final cost will depend on what those items turn out to be.

Check whether each allowance is realistic for what you want, and whether the builder will add overheads and profit when the actual cost is known. Our guide to provisional sums explains this in more detail.

4. VAT is unclear

Some quotations show VAT separately, some include it, and some do not mention it at all. If a builder is VAT registered, 20% on a large domestic project is a considerable sum. Make sure you know whether each figure is inclusive or exclusive of VAT, and whether any items are treated differently. If you are unsure how VAT applies to your particular project, take advice from an accountant or HMRC guidance rather than assuming.

5. The payment terms are front-loaded or open-ended

A reasonable deposit to secure materials or a start date can be sensible, particularly for items made to order. Be more cautious where a large proportion of the price is requested before meaningful work has been done, or where stage payments are not linked to identifiable progress.

Look for payments tied to clear stages — for example, foundations complete, roof on and watertight, first fix complete — and some agreement about how the final payment relates to snagging being finished.

Other things worth checking

• Is there a programme, or at least a start date and an expected duration?
• How long is the price valid for, and does it allow for material price changes?
• How will variations be priced and agreed — in writing, before the work is done?
• Who is responsible for building control, and is the fee included?
• Is the quotation based on the same drawings and specification as the others you have received?

What to do if you spot one of these

Ask the builder. Most will happily clarify, and the way they respond tells you a lot. Keep the answers in writing — an email is fine — so they form part of what you agree. If you have several quotations and they are hard to compare, it is often worth having someone independent look at them side by side before you choose.

That is what our Builder Quote Check is for: Caroline reviews two or three quotations for the same job, sets out the differences, gaps and risks, and gives you a list of questions to put to each builder before you appoint anyone. It is not legal advice, and it does not replace a proper contract — but it helps you make a clearer, better-informed decision.