A Real Builder's Quote, Annotated Line by Line (Good vs Bad)
What does a builder's quote actually look like, and where do the problems hide? Here is a realistic example quote annotated line by line, with the red flags a good check would flag.
Everyone tells you to "check your builder's quote", but almost nobody shows you what a real one looks like or where the problems actually hide. So here is a realistic example quote for a single-storey rear extension, annotated line by line. The numbers are illustrative, but every issue flagged is one we see constantly. By the end you will know what a good quote contains and what the gaps cost you.
The example quote
Here is the quote as the homeowner received it. Read it first, then we go through it.
| Item | Description | Price |
|---|---|---|
| 1 | Build single storey rear extension, approx 20m² | £38,000 |
| 2 | Kitchen units and worktops (allowance) | £6,000 |
| 3 | Electrics | £2,500 |
| 4 | Plastering | Included |
| 5 | Windows and bifold doors | £4,500 |
| Total | £51,000 + VAT | |
| Deposit required to start (50%) | £25,500 |
It looks professional. It has a letterhead, a total, and line items. It is also full of the gaps that cause disputes. Here is each one.
Line 1: "Build extension, approx 20m²" for £38,000
The biggest number on the quote is also the vaguest. £38,000 for "build extension" tells you nothing about what is and is not included. Does it cover foundations? Building control fees? The steel beam over the new opening? Making good where the extension meets the house? Waste removal and skips?
A single lump sum for the main build is the number one quote problem. It is impossible to compare against another builder, and it is where excluded items hide. A fair version breaks this into groundwork, structure, roof, and finishes, each with a price.
This is exactly the situation our how to read a builder's quote guide is written for: a number you cannot interrogate is a number you cannot trust.
Line 2: "Kitchen units (allowance) £6,000"
An allowance is not a fixed price. It is the builder's placeholder for something you have not chosen yet. That is legitimate, but it has to be flagged as what it is, because if you spend £9,000 on the kitchen, you owe the extra £3,000. The word "allowance" is doing a lot of quiet work here.
This is the same idea as a provisional sum: a figure that will be reconciled against actual cost, not a commitment. The quote should say so plainly, and ideally state how it is reconciled.
Line 4: "Plastering: Included"
"Included" in what? Included in the £38,000 lump sum? Then why is it a separate line? Vague inclusions like this are how the same item gets argued about later: the builder says it covered skim only, you assumed it covered making good the whole house after the works. Every "included" should say included in what, and to what standard.
The missing lines (this is the real problem)
What is not on the quote matters more than what is. None of these appear, and all of them cost money:
- Building control fees and the structural engineer for the beam calculations
- Making good: decoration and repair where new meets old
- Foundations beyond a vague "build" (ground conditions can move this thousands)
- Scaffolding and skips or waste removal
- VAT treatment beyond "+ VAT" (is everything standard-rated? any reduced-rate work?)
- A payment schedule beyond the 50% deposit
- Start date, duration, and what happens if it overruns
A quote that leaves these out is not cheaper. It is the same job with the awkward parts deferred to "extras" once you have committed.
The 50% deposit
A 50% deposit on a £51,000 job means handing over £25,500 before a brick is laid. If the builder does not return, or goes bust, that money is at serious risk. Fairer terms are a small deposit for materials, then stage payments tied to completed milestones (groundwork done, structure up, roof on, plastered, completed), with a 5% retention held until snagging is finished.
A large upfront deposit is one of the most common reasons homeowners lose money, and it is entirely avoidable with a proper stage payment schedule.
What the good version looks like
The same job, quoted well, would show: groundwork and foundations priced separately, the structural steel and engineer's fee itemised, building control fees listed, allowances and provisional sums clearly labelled, making good and decoration included or noted, VAT shown as a figure, and a stage payment schedule with a small deposit and a retention. It would also state the start date, the duration, and that it is a fixed quote, not an estimate. See what a builder's quote should include for the full checklist.
See your own quote checked like this
This is exactly what our quote check does, automatically. Upload your builder's quote and we go through it line by line: flagging vague lump sums, unlabelled allowances, missing items, deposit and payment terms, VAT clarity, and the building regs points most quotes skip, then we tell you where it stands against real UK benchmarks. It takes under a minute, and you can see a sample report first.
Spotting these problems before you sign is the difference between a fair job and an expensive lesson. For more warning signs, read signs your builder is overcharging.