How to choose a builder comes down to four things: pick a specialist for your type of project, check their insurance, references and finished work, compare detailed written quotes, and agree everything in a written contract before work starts. Get those right and most of the problems people dread, such as rising costs, delays and unfinished work, never happen.
We’re builders ourselves, so this guide is written from the other side of the fence. It covers how to choose a builder, the questions to ask, how to compare quotes, how to work together on site, what to do if things go wrong, and how to finish the project on good terms.
How to choose a builder you can trust
There is no official register of builders in the UK, and anyone can call themselves one. That’s why it pays to do your own checks. Here’s how to choose a builder with confidence.
Choose a builder who specialises in your type of work
A loft conversion, an extension and a kitchen refit need different skills. A general builder may be fine for small jobs around the house, but for a loft conversion you want a team that builds lofts every week. They’ll know the structural steelwork, the fire safety rules, the stair positions and the mistakes that cost homeowners money. The same goes for extensions; our guide to house extension mistakes shows what can go wrong.
Do your checks
- Reviews. Read reviews on more than one site, such as Google, Houzz and trade bodies, not just the builder’s own website.
- Recommendations. Ask friends and neighbours who have had similar work done, but still check the builder suits your project.
- Trade bodies. Membership of a body such as the Federation of Master Builders or TrustMark means the builder has been vetted and gives you a complaints route if things go wrong. Be wary of referral sites that charge builders commission for leads.
- Finished work. Ask to see recent projects, and to speak to past clients. A good builder will be happy to arrange it.
- Insurance. Ask for proof of public liability insurance. Without it, you could be held responsible if someone is injured on your property.
Three signs to look for when you choose a builder
In our experience, a good builder:
- Can’t start tomorrow. Good builders are usually booked up for weeks or months ahead.
- Won’t price the job on the spot. They’ll visit, measure and ask questions before giving you a written quote.
- Isn’t the cheapest. Quality work and proper materials cost money. A quote far below the others usually means corners will be cut or extras will appear later.
Red flags
- Asking for a large payment upfront, or cash only
- No written quote, contract or address
- Pressure to decide quickly or “start Monday”
- No insurance, or reluctance to show it
- Telling you that you don’t need planning permission or Building Regulations approval without checking
Questions to ask when you choose a builder
Shortlist two or three builders and ask each one the same questions. Their answers, and how willingly they give them, tell you a lot.
- Do you specialise in this type of work? How many similar projects have you finished in the last year?
- Can I see your last few projects, and speak to those clients?
- Are you insured? Ask for public liability insurance, and check who insures the building works while they’re in progress.
- Are you a member of a trade body? Which one, and does it offer a complaints or dispute service?
- What exactly does your price include, and what doesn’t it? Drawings, structural calculations, planning and Building Control fees, party wall costs, skips, scaffolding, decorating and making good.
- Is the price fixed? What could change it, and how will extra work be priced and agreed?
- Who will be on site every day, and who do I contact? Will you use subcontractors?
- How long will the job take, and when can you start?
- Who handles planning, Building Control and party wall notices? For a loft, these should be part of the service. See our guides to planning permission, loft conversion plans and party wall notices.
- Will there be a written contract?
- What guarantee do you give on the work? Specialist loft companies typically offer a guarantee of around 10 years; many general builders offer none.
- How will the work affect my neighbours, and can I stay at home during the build?
How to choose a builder by comparing quotes
Get at least three written quotes, and make sure every builder is pricing the same thing. The easiest way is to give them all the same drawings and specification.
| Check | What to look for |
|---|---|
| Is it itemised? | A good quote breaks the work into stages and lists materials, not one total on a single line. |
| What’s excluded? | Look for fees left out to make the price look lower: architect, structural engineer, planning, Building Control, party wall surveyor, skips, scaffolding, decorating. |
| Is it a quote or an estimate? | A quote is a fixed price for the work described. An estimate is a best guess that can go up. |
| Provisional sums | Items priced as an allowance, such as a bathroom suite, can change. Check the amounts are realistic. |
| Timescale | A start date and a realistic programme of work. |
| Payment terms | Stage payments tied to work completed, not large sums upfront. |
The thoroughness of a quote is often a good guide to the quality of the work. A detailed quote shows the builder has thought the job through.
Why the cheapest quote often costs more
There is a minimum price any job can honestly be built for. When a quote is well below the others, the difference has to come from somewhere: cheaper materials, fewer people on site, missing items that reappear as extras, or a builder who loses interest because the job isn’t paying. A roof that leaks or a heating system that can’t cope will cost far more to put right than the money saved at the start. Never choose a builder on price alone. We always give one fixed price, agreed before work starts.
Contract, payments and insurance
Always have a written contract
Once you choose a builder, put everything in writing. A contract protects you and the builder. It should set out the work, the drawings and specification, the price, the payment stages, the start and finish dates, how changes are agreed and priced, and the guarantee. Standard home owner contracts are available from the JCT and the Federation of Master Builders, and many specialist builders use their own.
Pay in stages
- Avoid large upfront payments. A small deposit to book your slot or order materials is normal; paying most of the price before work starts is not.
- Tie payments to progress. For example, after the steelwork, at the watertight stage, after first fix and at completion.
- Keep back a small retention. Many contracts hold back a small percentage, often around 5%, until the snagging is finished.
- Pay on time. Prompt payment of each agreed stage keeps the job moving and the relationship good.
Check the insurance
- Public liability insurance covers injury or damage to people and property caused by the builder.
- Contract works insurance covers the building work itself, for example storm damage to a half-built roof. Check whether the builder holds it.
- Your own home insurance. Tell your insurer before building work starts, as major works can affect your cover.
How to work well with your builder during the project
Once you’ve chosen a builder, the way you work together makes a big difference to how smoothly the job goes. These habits help on every project we build.
- Use email for decisions. Phone calls are fine day to day, but anything that affects the work, the cost or the finish should go by email, not text or WhatsApp. It gives you both a clear record. Builders often deal with email at set times, so don’t worry if a reply takes a few hours.
- Save questions for a weekly site meeting. Rather than messaging every idea as it comes, keep a list and go through it at a regular meeting on site. Keep it within working hours, so the builder isn’t fielding calls in the evening.
- Confirm what was agreed. After each meeting, send a short email listing what was agreed and who is doing what. It catches misunderstandings before they’re built in.
- Agree changes in writing. If you change your mind about something, ask for the cost and any delay in writing before the work is done. Changes are the most common cause of arguments about the final bill.
- Make decisions on time. Choosing tiles, sanitaryware and finishes early keeps the job moving; late decisions cause delays.
- Respect the site. Keep children and pets away from work areas, and let the builder know about anything that affects their work, such as a freshly mopped floor.
- Keep it professional and positive. You’re in charge, and the tone you set on site matters. Raise genuine concerns straight away, but a friendly relationship makes everyone work better.
Avoiding and resolving disputes with a builder
Small problems vs serious ones
On any build, small things go wrong: a leak when the water is reconnected, a scuffed wall, a damaged item. Report these to the builder promptly, in writing, with a photo. Most will be fixed as part of the job or at the snagging stage.
The serious disputes usually come from four things:
- Poor-quality work. Under the Consumer Rights Act 2015, a trader must carry out a service with reasonable care and skill.
- Rising costs. Often from a low initial quote, or changes that weren’t priced and agreed in writing.
- Delays. From a builder spread across too many jobs, or late materials.
- Unfinished work. A builder who leaves before the job is done.
Knowing how to choose a builder carefully, with a clear contract and fixed price, prevents most of these.
What to do if things go wrong
Keep everything in writing, take photos and keep a log as you go. Then work through these steps, moving on only if the one before doesn’t work:
- Raise it with the builder in writing and give them a reasonable chance to put it right. Avoid criticising them on social media while you’re still trying to resolve it.
- Use the trade body’s complaints or dispute service, if the builder belongs to one. If not, Citizens Advice can tell you your options.
- Send a letter before action. This is a formal letter setting out the problem and saying you’ll go to court if it isn’t resolved.
- Take legal advice. For claims up to £10,000 in England and Wales you can make a small claim yourself; for larger or complex disputes, use a solicitor who handles domestic building cases.
This is general guidance based on our experience, not legal advice.
Finishing the project on a high
The end of a build is when good relationships are tested. These steps help you finish well:
- Walk round and snag together. List anything that needs finishing or correcting, and agree a date to fix it. Our snagging guide explains how to do it properly.
- Get the paperwork. Make sure you have the Building Regulations completion certificate, electrical and gas safety certificates, warranties and any guarantees before the final payment.
- Pay the final instalment promptly once the work is done. Don’t hold back money over very small items; agree them as snags instead.
- Be patient with extras. If you’d like more work done, your builder may already be booked on their next job, so expect to wait a little.
- Let them photograph the work. Builders rely on photos of finished projects to show future clients.
- Leave a review. If you’re happy, a Google review or a recommendation to friends means a great deal to a small business.
- Be a reference. Agreeing to show a future client your finished room is one of the best thank-yous you can give.
FAQs
What is the best way to choose a builder?
The best way to choose a builder is to shortlist two or three specialists for your type of work, check their reviews, insurance and finished projects, compare detailed written quotes for the same specification, and agree a written contract with a fixed price and stage payments.
How many quotes should I get from builders?
At least three. Give every builder the same drawings and specification so you can compare like with like, and be wary of any quote that’s far cheaper than the rest.
How much deposit should I pay a builder?
Keep it small. A modest deposit to secure your start date or order materials is normal, but avoid paying a large share of the price before work begins. After that, pay in stages as the work is completed.
What’s the difference between a quote and an estimate?
A quote is a fixed price for the work described. An estimate is the builder’s best guess, and the final cost can be higher. For a loft conversion or extension, always ask for a fixed quote.
Do I need a contract with my builder?
Yes. A written contract sets out the work, price, payments, timescale and guarantee, and protects both of you if there’s a disagreement.
What can I do if my builder does poor work?
Raise it with the builder in writing first and give them a chance to fix it. If that fails, use their trade body’s dispute service, send a letter before action, and then take legal advice or make a small claim.
Should I use a specialist loft conversion company or a general builder?
For a loft conversion, a specialist is usually the safer choice. Knowing how to choose a builder for the job matters: lofts involve structural steelwork, fire safety rules, stairs and party wall work that a specialist deals with every week.
Looking for a loft conversion builder in London?
If you’re working out how to choose a builder for your loft, talk to us. We’re a specialist loft conversion company, and we’re happy to answer every question on this page. We handle the design, planning, Building Control and party wall notices, give you one fixed price before work starts, and guarantee our work. You can read more about why homeowners choose us.
