Picking the right builder matters more than picking the cheapest quote

What to check before you commit

Ask for proof of public liability insurance and, where relevant, professional indemnity cover if the builder is also providing design input. Check whether the firm is a limited company or a sole trader, since this affects your position if something goes wrong, and ask how long they have operated under their current trading name.

Photographs of previous work, ideally similar in scale to your project, tell you more than generic marketing claims. If you can see a completed extension or loft conversion in person, even better, since photos can flatter finishes that look different up close.

Comparing quotes fairly

Two quotes for the same brief can differ substantially if one includes items the other has left out, such as scaffolding, skip hire, making good to existing decor, or specific fittings. Ask each builder to itemise so you are comparing like with like rather than assuming the cheaper number represents the same scope of work.

Be cautious of a quote that is significantly lower than the others without an obvious reason, since it can indicate corners being cut, under-specified materials, or a builder who intends to recover the shortfall through variations once work is underway.

Communication and site conduct

Ask how updates will be communicated during the job, whether that is regular site visits, phone calls, or written updates at key milestones. A builder who is hard to reach before you have signed anything is unlikely to improve once the contract is agreed.

Site conduct matters too, particularly for occupied homes: how the team protects floors and furniture, keeps noise and dust to reasonable hours, and treats neighbours during work that might affect them, such as scaffolding on a shared boundary or deliveries blocking a narrow street.

Contracts and payment structure

A clear payment schedule tied to project stages protects both sides, rather than large sums requested upfront before work has started. Ask what happens if the scope changes, how variations are priced, and what the process is if a dispute arises over quality or completion.

For larger projects, a written contract setting out the programme, payment stages and responsibilities is worth having in place before work begins, even between parties who already trust each other.

Common questions