Two builders can quote the same house in good faith and land thousands apart, because they have priced different jobs. These are the questions that make the numbers mean the same thing.
Is that inclusive or exclusive of VAT?
Ask everyone, every time. The FMB names this first: always ask whether the quote includes VAT and whether there are any other costs not mentioned.
Twenty per cent is larger than the gap you are usually trying to judge between firms. If one builder quotes no VAT at all, the innocent explanation normally applies: the registration threshold is £90,000 of taxable turnover, so a small sole trader charges none. That is lawful. A registered firm offering to switch VAT off for cash is a different matter entirely.
What is not in this figure?
The second half of the FMB's question is the one people forget. On a London job the usual omissions are:
- Skip hire and waste removal, and the borough licence if the skip sits on the highway. Southwark charges £105 a month for a skip licence, a council fee rather than a trade rate.
- Parking. In a controlled parking zone, permits or bay suspensions are a daily cost, and suspensions need advance notice to the council.
- Scaffolding or access equipment, and who holds the contract with the scaffolder.
- Specialist trades: electrical, gas, structural engineering, party wall surveying.
- Building control fees, and any planning or consent costs.
- Making good and decoration after the structural work finishes.
A quote that includes all of these looks worse than one that excludes them and adds them in month two. Ask each builder to price the same list.
Can you separate labour and materials?
The FMB suggests asking for this specifically, and it is the change that makes comparison possible. Two identical totals can conceal a very different balance between rate and markup, and you cannot see it until the lines are apart.
While you are there, settle who orders the materials. The FMB lists this among the things to discuss before signing. Citizens Advice makes the case for buying them yourself where practical, on the basis that at least you own the materials if something goes wrong.
What is the rate for extras and overruns?
The FMB's contract checklist calls for the full agreed price including rates for extras and overruns. Agree that before work starts, not when a variation is already halfway built.
Ask the related question too: who authorises a variation, and in what form? A change agreed verbally on site between your partner and a subcontractor is the origin of a very large share of building disputes. Agree that variations are confirmed in writing and priced before they proceed.
Is this a quote or an estimate?
Citizens Advice uses the words this way: a quote means a fixed price, so you know what you are getting and how much it will cost, and an estimate is a considered guess. That is convention rather than statute. No legislation defines either word, so the heading on the paperwork decides nothing by itself. What decides who carries the overrun is whether a price was agreed. Section 51 of the Consumer Rights Act 2015 gives you a reasonable price and no more, but only where no price was agreed at all; once you have agreed a figure, that figure is what you owe.
Ask which you have been handed, and ask for it in writing. Quotes, as the FMB says, should always be written and never verbal.
What happens if it overruns?
Ask whether the contract will include liquidated damages, a pre-agreed rate for delay that the FMB recommends. It is far easier to agree a figure before anyone is late than to argue about compensation afterwards.
Ask for a programme with dates, and ask what the completion date depends on. If the date matters to you, say so at the point of contracting and get it recorded, because that changes your legal position later.
What is the payment schedule, and what does the deposit buy?
Ask for staged payments tied to completed, verifiable stages, with the final payment falling due on completion after snagging. Citizens Advice recommends staged payment precisely because it lets problems be put right before you pay the balance.
On the deposit, ask what it is for. The FMB says a 10% deposit is reasonable and not to pay more than 25%, and Citizens Advice independently gives the same 25% ceiling.
Insurance, party walls and the things nobody can see yet
Ask whether anyone will be working for the builder on this job, then ask for the employers' liability certificate if so, and the public liability certificate regardless. Check the entity named on it matches the entity invoicing you.
Ask whether the work engages the Party Wall etc. Act 1996. In terraced and semi-detached South London most structural work touching a shared wall does, and where a neighbour dissents you pay for the surveyors. On a mid-terrace that can mean two neighbours.
Finally, ask what happens if the joists, the drains or the foundations are worse than expected. A quote with no provisional sum for the unknown is incomplete rather than competitive.
Ask every builder on your shortlist the same list in the same order.