How the check works

You upload the quote as a PDF, a photo or a Word document. A language model (Claude, made by Anthropic) reads it and writes out what it found in a fixed structure: each line item and its price, the totals and the VAT treatment, the deposit and any stage payments, how long the quote is valid, the guarantee, the builder's stated exclusions and assumptions, any provisional sums or allowances, and any trade registrations the quote mentions. If the document is a scan or a photo, the model reads the image directly.

The totals are then checked by ordinary code, not by the model: whether the line items add up to a total the quote prints, and whether the quote states a VAT-inclusive figure at all. A quote whose lines do not reconcile with its total is flagged so you can ask the builder about it. The check does not read quantities, units or rates on each line, so it cannot tell you whether an individual line is priced fairly; it works from the descriptions and the line totals.

A model can misread a figure or miss a line, and a poor scan makes that more likely. The report shows you the lines it read so you can compare them with the paper in front of you. A document that cannot be read as a builder's quote at all is deleted straight away and no check is run.

For each kind of job we keep a checklist of the work that quotes for that job usually price: for an extension, items such as foundations, drainage, structural steel, scaffolding, building control fees, making good and waste removal; for a bathroom, items such as first-fix plumbing, tanking, tiling, ventilation and the sanitaryware itself. The checklists are written by us and cover extensions, lofts, kitchens, bathrooms, re-roofs, rewires and the common single-trade jobs.

The lines the model read are set against that checklist, and each checklist item comes out as included, unclear, or not mentioned. Work the builder has excluded in writing is not counted as missing: the builder has told you it is not included, so the report lists it separately, under “Excluded by the builder”, with whether a job like yours usually needs it and, where we can, what it typically costs. Each figure says where it comes from: the builder's own price when their quote names one, a typical UK cost from our rate card, or a rough estimate. A stated exclusion is a known cost you can plan for; a silent gap is a question for the builder.

The checklist is generic to the job type. It does not know your site, your drawings or what you have agreed verbally, so an item it lists as missing may be one you have arranged separately, and an item it does not list may still matter for your job.

The regulatory findings come from two places. A set of fixed checks, written by us, looks for the points that recur on jobs of each type: a structural opening with no line for calculations or building control, electrical work that is notifiable, a new bathroom with no extract ventilation, and so on. Alongside them, the model reads the quote against a corpus of England's Approved Documents and a small number of other published rules, such as the Party Wall etc. Act 1996 and the Gas Safety and Water Fittings regulations.

Every regulatory finding names the Approved Document part it comes from. When the finding also cites a clause, that clause reference and the quoted text were checked against our copy of the document, and the finding carries a link to that document on gov.uk. When the finding names a part but no clause, the match could not be made and we would rather show less than show a clause we could not verify. A citation means the rule exists and says what the finding says it says. It does not mean the rule applies to your job, and it is not a building control decision; only a building control body can make one.

The rules we analyse are England's unless the finding says otherwise. Wales, Scotland and Northern Ireland have their own building standards, and a finding may not apply to a property outside England. The corpus is updated by hand, so a recent change to a document can lag.

The benchmark is a modelled cost band for the whole job. It is built from published UK cost guides (Checkatrade, MyJobQuote, Which? and trade price guides) for each trade at three specification levels, multiplied by a regional labour-rate factor for your area, and sized by the job type, its floor area where the quote or you give one, and the specification level read from the quote. Where the quote gives no specification, the standard level is assumed. The estimator records a confidence grade for each band, and where it cannot support a band for a job (an unusual job type, or a total wildly out of proportion to the estimate) the report shows no range rather than a weak one.

The check sets the quote total against that band and tells you whether the whole figure sits below, inside or above it. It does not benchmark each line, and it does not benchmark each trade within the quote.

What the benchmark is not: it is not BCIS, Spon's or any other subscription cost database; it is not a set of real quotes from your postcode; and it is not a survey or a valuation. A band built from published guides is wide, and a quote inside it can still be a poor quote, or a good one. Treat the position against the band as one input to a conversation with your builder, not as a verdict on their price.

When a project holds more than one quote, the report puts them on the same basis. For each item the job type's checklist treats as important, a quote that leaves it out has an allowance added, from the first of these that exists: the builder's own price for that work, where their quote names one; a typical UK cost from a short rate card of the common items, such as a skip, decoration, a building control fee or scaffolding; or, where a whole trade is missing, the benchmark's typical cost for that trade. Each allowance says where it came from, and each is a typical figure, not a quote.

Not every gap can be costed. When a gap has no builder's price, no rate card entry and no whole-trade benchmark, the report says it is not yet costed and does not claim which quote is cheaper for the same work: it tells you which is cheapest as quoted, and how many items it could not cost. Only the items the checklist treats as important are priced at all, so read the list of what each quote leaves out beside the figures.

Produced by a language model: the reading of the document, the scope findings and the regulatory findings that come from the model's read, and the written summaries and the questions to ask your builder. These are the parts that can be wrong in the way a person skimming a document can be wrong: a misread figure, a missed line, an overconfident sentence.

Ordinary code, the same every time: the arithmetic checks on the totals, the benchmark band and the regional factor, the fixed regulatory checks, the allowances for missing work, the reconciliation of every count shown on a page, and the citation verifier that keeps a clause reference only when it matches the corpus exactly.

No person reviews a report before you see it. We word findings to how sure we are: a flat statement where the rule is certain, “looks” or “appears” where it is not, and a question for your builder where we are unsure. The fixed checks enforce that grading; a finding the model wrote can overstate, which is one reason to confirm it with your builder.

• It does not visit your property, read your drawings, or know what you have agreed with the builder in person.
• It does not verify the builder: it notes registrations the quote mentions and ones it would expect, and it does not check them against the registers.
• It does not price each line or each trade within the quote. It sets the whole total against a modelled band.
• It does not decide whether work complies with the Building Regulations. That is for your building control body.
• It is not a survey, a valuation, a quantity surveyor's report, legal advice or financial advice.
• It can be wrong. Confirm any finding with your builder before you act on it, and, where it matters, with a professional.

The terms of service say the same in the words that bind us, and the privacy policy says what happens to the document you upload.