Before you hire a builder, ask who they are, what insurance they hold, who will actually be on site, who deals with Building Control and the party wall, how you will pay, and what happens if something goes wrong. Then check the answers yourself rather than taking them on trust. Companies House, HMRC's VAT checker, the Gas Safe Register and the competent person scheme registers are all free and take minutes.
There is no licensing of builders in England. Anyone can buy a van and some business cards. An FMB survey published in 2025 found that nearly half of the public wrongly believe licensing already exists, and Citizens Advice's figures for the year to August 2026 put roofing as the single most reported scam to its consumer service — most of them starting with a knock on the door. So the checks below are not paranoia. They are the only vetting that happens.
We would rather you asked us every one of these. Here they are, with what a good answer sounds like and how to check it.
1. Who exactly am I contracting with?
You want a name, a trading address and a landline as well as a mobile. If it is a limited company, ask for the company number and look it up on Companies House. It costs nothing and shows you whether the company is active, when it was formed, who the directors are and whether its accounts are overdue.
A sole trader can be every bit as good as a limited company. What matters is that you know who is legally on the other side of the contract, and that you can find them if you need to.
Ours, for comparison: Swanbourne Construction Ltd, company number 16870716, Unit 27 Middleton Business Park, Yapton Road, Middleton-on-Sea, PO22 6HS.
2. Are you VAT-registered, and is the price including VAT?
If the builder charges VAT, the number should be on the quote and you can check it is genuine with HMRC's VAT number checker, which shows the name and address it is registered to. The registration threshold is £90,000 of turnover a year, so a firm doing a lot of extension work and charging no VAT is either small or should be asked why. More on reading VAT in a quote in how to compare builders' quotes.
3. What insurance do you hold — and can I see it?
Three kinds matter:
- Employers' liability. This one is the law. Any business that employs people must hold at least £5 million of employers' liability cover from the day it becomes an employer, with narrow exemptions such as a business employing only close family.
- Public liability. Not compulsory, but essential. It covers injury to people and damage to property — your house, or next door's — caused by the work. Ask how much; £2m is a common level for domestic building.
- Contractors' all-risk covers the works themselves until they are handed over, so a fire or a storm during the build does not become your problem.
Ask to see the certificates, and check the dates run past your finish date. Then ring your own home insurer and tell them about the work before it starts. Which? has warned that undeclared structural work can affect buildings cover.
4. Can I see similar jobs and speak to the clients?
Written references can be invented. A phone call to someone who had a similar job done eighteen months ago is much harder to fake, and so is standing in a finished room. Ask for two or three recent jobs of the same kind as yours — a loft if you want a loft, an extension on a bungalow if that is what you have.
Better still is a job that is on site now, because that shows you how the builder works rather than how the finished photograph looks: how tidy the site is, how the occupied part of the house is protected, whether the scaffold is sheeted. We publish what we are currently on site with and will arrange a visit where the household agrees.
5. Who will actually be on site, and who runs the job?
The person who sells you a job is not always the person who runs it. Ask who will be on site day to day, who you ring when something goes wrong, and which trades are subcontracted. Subcontracting is normal — very few firms employ their own roofer, plasterer, electrician and gas engineer — but you should know who is coming, and the main contractor stays responsible for their work.
Ask too about working hours and welfare: will the builder bring a toilet, or use yours by agreement? Councils locally, including Chichester District Council, publish guidance on noisy construction work of 8am to 6pm on weekdays and 8am to 1pm on Saturdays, with none on Sundays or bank holidays.
6. Who does the gas and electrics, and are they registered?
Gas work must, by law, be done by an engineer on the Gas Safe Register. Check the engineer's ID card and that they are registered for the kind of work involved. Most electrical work in a new room or a bathroom is notifiable under Part P of the Building Regulations, which means either Building Control inspects it or it is done by an electrician registered with a competent person scheme such as NICEIC or NAPIT, who self-certifies it.
Ask who will issue the certificates, and make sure you get them at the end. On our jobs the gas and electrical work is done by registered installers who certify it under their own registration, and we tell you who they are before they start.
7. Who applies for Building Control, and who pays?
Almost every extension, loft conversion, garage conversion and structural alteration needs Building Regulations approval, whether or not it needs planning permission. Ask:
- Who submits the application — Full Plans or a Building Notice?
- Who books the inspections, and who meets the inspector?
- Who pays the fee? (The fee usually goes from you to the council.)
- Will I get the completion certificate at the end?
Since 1 October 2023 the Building Regulations have carried a "dutyholder" regime. For a domestic client, the duty to make sure the work complies passes to the contractor, or to the principal contractor and principal designer where there is more than one firm. That does not stop you cooperating and sharing information. It does mean a builder who suggests "doing it without Building Control" is asking you to carry a risk that is meant to be theirs — and it will surface when you sell. Our guide to loft conversion building regulations explains why.
8. Does this need planning permission, and who has checked?
Many single-storey rear extensions and loft conversions are permitted development, but not all, and the exceptions are where the trouble is: conservation areas, the South Downs National Park, houses whose permitted development rights were removed when the estate was built, and extensions that have already used up the allowance. Ask the builder how they know. "Everyone round here has done one" is not an answer. A Lawful Development Certificate is. See planning permission for rear extensions and for loft conversions.
9. Does the Party Wall Act apply, and who serves the notices?
If the work touches a shared wall, builds on the boundary, or digs foundations close to next door, the Party Wall etc. Act 1996 probably applies. Notices go out from you, as the building owner, one or two months before work starts depending on the type of work. Ask whether the builder has allowed for that in the programme. Our party wall guide has the detail.
10. How will you manage health and safety?
The Construction (Design and Management) Regulations 2015 apply to domestic jobs. As a homeowner your client duties pass automatically to the contractor (or principal contractor). The HSE still expects you to make reasonable enquiries about a builder's approach to safety and to allow enough time and money for the job to be done safely. Ask to see the construction phase plan. It should be proportionate — a page or two for a bathroom, more for an extension — but it should exist.
11. What is the programme, and what happens if it slips?
Ask for a start date, a finish date and the main stages in between. Ask what typically delays this kind of job and how the builder deals with it — weather on a roof, lead times on glazing, Building Control inspections. If no completion date is agreed, the Consumer Rights Act only gives you "a reasonable time", which is a harder thing to hold anyone to.
12. How much is the deposit, and how will I pay after that?
Citizens Advice suggests not agreeing to a deposit of more than 25%. After that, payments should follow work done — staged against milestones or valued every week or two — so you are never ahead of the job. Pay by bank transfer to a business account or by card, never cash. Ask whether any money is held back as retention until the snagging is finished.
Ours: a 5% deposit, fortnightly valuations of work actually done, and 5% retention released at practical completion.
13. How are changes priced and agreed?
Something always changes. The good answer is that every variation is priced in writing and agreed before the work is done, at a day rate or a quoted figure. The bad answer is "we'll sort it out at the end".
14. What guarantee do I get, and is it insurance-backed?
A builder's guarantee is a promise to come back and put defects right for a set period. It sits on top of your legal rights under the Consumer Rights Act; it does not replace them. Ask how long it runs, what it covers, and whether it passes to a buyer if you sell.
An insurance-backed guarantee is different: it is an insurance policy that pays for defects to be put right if the builder has stopped trading. Read the terms, because cover is often capped and some policies exclude consequential damage. Ours is a 24-month workmanship guarantee from the company, with manufacturers' warranties passed on in full; it is not insurance-backed, and we would rather say so plainly than let you assume otherwise.
15. Where does the waste go?
Anyone carrying waste away from your job must be a registered waste carrier with the Environment Agency, and householders have a legal duty of care to pass their waste only to someone authorised. If your rubbish is fly-tipped by an unregistered carrier, you can be fined. Ask for the registration number and check it on the Environment Agency's public register. Ask whether skips are in the price, and whether a skip on the road needs a permit — in West Sussex that comes from the county council.
What about TrustMark, the FMB and Buy With Confidence?
Membership of a scheme tells you a business has been through some vetting and has a complaints route. TrustMark is the government-endorsed scheme for work in the home; the Federation of Master Builders requires members to use written contracts; West Sussex Trading Standards runs Buy With Confidence. None of them guarantees a good job, and logos are easy to copy, so check membership on the scheme's own website. Plenty of good builders belong to none of them — which is exactly why the fifteen questions above matter more than a badge.
Warning signs
- Turning up uninvited, especially to tell you something is wrong with your roof.
- A mobile number and nothing else.
- Reluctance to put the quote, the contract or the insurance in writing.
- Cash only, or a discount for cash.
- A large payment before anything happens on site.
- "We don't need Building Control for this."
- Pressure to decide today.
- No references, or references you cannot speak to.
If something goes wrong
Raise it in writing with the business you contracted with, even if a subcontractor did the work. Say what is wrong, what you want done, and give a reasonable deadline; take photographs and keep dated notes. Under the Consumer Rights Act you can ask for the work to be put right at the builder's cost first, and if that fails, a price reduction. If that gets nowhere, a trade body's dispute scheme or the small claims court are the next steps, and the Citizens Advice consumer service can help and refer rogue traders to Trading Standards.
Questions people ask about choosing a builder
How do I check if a builder is legitimate?
Look the company up on Companies House, check any VAT number with HMRC's free checker, ask to see insurance certificates, speak to two or three recent clients, and visit a job if you can. Check any trade body membership on the scheme's own website.
What insurance should a builder have?
Employers' liability is a legal requirement for any builder with employees, at a minimum of £5 million. Public liability is not compulsory but you should insist on it, because it covers damage to your home and your neighbours'. Contractors' all-risk covers the works until handover.
Is the builder or the homeowner responsible for building regulations?
Both have a part, but for domestic work the duty to make sure the work complies passes to the contractor, or to the principal contractor and principal designer on larger jobs. As the homeowner you still need to cooperate and share information, and it is your property that is affected if the paperwork is missing when you sell.
Does CDM apply to a home extension?
Yes. The Construction (Design and Management) Regulations 2015 apply to domestic work, but a homeowner's client duties pass automatically to the contractor, or the principal contractor where there is more than one. You should still check the builder takes safety seriously and has a construction phase plan.
Do builders need to be licensed in England?
No. There is no general licensing scheme for builders, which is why your own checks matter. Gas work is the exception — it must be done by a Gas Safe registered engineer — and notifiable electrical work needs either Building Control or a registered competent person.
What is an insurance-backed guarantee?
An insurance policy that pays to put defects right if the builder who did the work has stopped trading and cannot honour their own guarantee. Cover is often capped and terms vary, so read the policy. It is separate from the builder's own workmanship guarantee and from your legal rights.
Should I use a builder who knocks on my door?
Be very wary. Citizens Advice found that 77% of suspected roofing scams reported to it in the year to August 2026 involved doorstep selling. A reputable builder will not mind you getting other quotes and checking them out first.
What can I do if my builder does a bad job?
Complain in writing to the business you contracted with, set out what you want and give a reasonable deadline. You are entitled to have the work put right at their cost, and failing that to a price reduction. If that fails, use the trade body's dispute service or the small claims court, and contact the Citizens Advice consumer service.
Where these facts come from
- GOV.UK: employers' liability insurance — the £5 million minimum.
- Citizens Advice: before you get building work done — insurance, references, deposits, payment.
- Citizens Advice press release, October 2026 — roofing scam figures.
- HSE: CDM 2015, domestic clients.
- GOV.UK: competent person schemes.
- GOV.UK: party walls and building work.
- TrustMark: about the scheme.
- Federation of Master Builders, 2025 survey on licensing.
Price match guarantee
We will never compromise on quality but we will match any like-for-like price.
The words doing the work there are like-for-like. A quotation that comes in cheaper is usually describing a different job underneath. A shallower footing. A thinner unit of glass behind the same three words. Making good dropped, so the decorating lands back on you at the worst possible moment. A scaffold nobody priced, arriving in week three as an extra.
None of that makes the other builder a crook. It makes the two pieces of paper impossible to compare until somebody opens them both up, which is the whole reason ours arrives as over two hundred itemised lines rather than a figure at the bottom of a page.
So bring the other quotation to the site visit and we will go through it against ours, line for line. Either your price gets matched, or you find out what the cheaper number quietly leaves out — and either of those is worth an hour.
Read the price match guarantee terms — what counts as like-for-like, how long a match holds good, and why one builder's total can sit a fifth below another's before anybody has lifted a tool.
Related guides
How to compare builders' quotes line by line
Quote or estimate, provisional sums, exclusions, VAT and payment terms — how to put two prices side by side and see the same job.
Read the guideLiving at home during an extension or renovation: what to expect
Dust, noise, kitchen downtime, builders' hours, toilets, skips, your insurer and asbestos — and when moving out is genuinely worth it.
Read the guideParty wall agreements explained for homeowners
The three kinds of work that need a notice, the notice periods, the 3m and 6m rules, what happens if the neighbour says no, surveyors' fees and who pays.
Read the guideNext step
If the drawings exist, send them and a priced quotation comes back. If they do not, the site visit is the way to find out whether the job can be done at all.
Or the landline on 01243 256796, or WhatsApp if it is easier to send a photograph. Reply within one working day, every time.