How to Choose a Builder in London — The Complete Checklist Primary keyword: how to find a good builder London URL slug: /blog/how-to-find-a-good-builder-london Word count: approx 1,010

How to Choose a Builder in London — The Complete Checklist

Finding a good builder in London is one of the most consequential decisions you will make for your home. Get it right and you'll have a smooth, professionally managed project that adds real value to your property. Get it wrong and you risk delays, poor workmanship, budget overruns, or — in the worst cases — a contractor who disappears with your deposit mid-project.

The London construction market is large and varied. There are excellent contractors, average ones, and some who are genuinely dangerous to hire. This guide gives you a practical 10-point checklist for how to find a good builder in London, along with the red flags that should stop you in your tracks.

1. Check Accreditations

Membership of recognised industry bodies tells you that a contractor has been vetted, operates with proper insurance, and is accountable to a defined code of conduct. The key accreditations to look for are:

• Federation of Master Builders (FMB): Members are assessed on technical competence and financial standing. The FMB also provides a dispute resolution service for clients.
• TrustMark: A government-endorsed quality scheme covering tradespersons working in and around the home.
• Checkatrade / TrustATrader: Consumer-facing platforms where contractors are vetted and customer reviews are independently verified.

Accreditations don't guarantee perfection — but they do create accountability. That matters.

2. Verify Insurance

Any contractor working on your home must hold, at a minimum:

• Public Liability Insurance: Covers damage to your property or injury to a third party caused by their work. A minimum of £2 million is standard; £5 million is preferable for larger projects.
• Employers' Liability Insurance: A legal requirement for any contractor who employs staff.

Ask to see current insurance certificates — not just a verbal assurance. Uninsured construction work can leave you with significant liability.

3. Ask for References and Call Them

Any established contractor should be able to provide references from recent, comparable projects. Ask for at least two or three — and actually call them. The questions that matter most are:

• Was the project completed on time and within budget?
• How did the contractor handle problems when they arose?
• Would you use them again?

A contractor who is reluctant to provide references, or whose references are vague, should give you pause.

4. Request a Written Scope of Works — Not Just a Price

A price figure in isolation tells you very little. Two quotes for a loft conversion can differ by £20,000 or more simply because they include different things. Always ask for a written scope of works that clearly sets out:

• What is included
• What is excluded
• Whether materials are contractor-supplied or client-supplied
• The assumptions the price is based on

A contractor unwilling to provide this level of clarity is a contractor who will not manage your project clearly either.

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5. Check Companies House Registration

Any limited company's registration, directors, and filing history can be verified free of charge at Companies House (companieshouse.gov.uk). Look for:

• How long the company has been registered
• Whether accounts are filed and up to date
• Whether there are any county court judgements or dissolution notices

Sole traders cannot be checked this way, but limited companies should have a verifiable, consistent record.

6. Agree a Written Contract

Never proceed without a written contract — even for smaller jobs. A sound construction contract should cover:

• Scope of works and contract sum
• Any provisional sums or contingency allowances
• Payment schedule tied to milestones
• Programme and key dates
• How variations and scope changes will be managed
• Dispute resolution procedure
• Retention terms and release conditions

Industry-standard forms such as JCT Minor Works contracts are widely used for domestic projects and provide a clear, familiar framework.

7. Understand the Payment Schedule

A fair payment schedule is structured around project milestones — not a contractor's cash flow requirements. Expect to pay a deposit to mobilise (typically 10–20%), then staged payments tied to measurable progress, with a retention held until practical completion.

Never pay the full contract sum upfront. Never pay in cash. Any contractor who demands full payment before work begins is operating in a way that removes your protection entirely.

8. Check VAT Registration

For projects above a certain value, contractors should be VAT-registered. VAT registration becomes a legal requirement once a business exceeds the registration threshold. If a contractor operating at a clear scale is not VAT-registered, this raises questions about how their business is managed more broadly and whether they are operating compliantly.

9. Ask About Subcontractor Management

Most contractors on larger projects will use specialist subcontractors for trades such as plumbing, electrics, and roofing. This is entirely normal and expected. The key question is: who manages those subcontractors, and who is accountable if something goes wrong?

A principal contractor takes full responsibility for the whole project — coordinating subcontractors, maintaining standards, and remaining your single point of accountability. A loose group of individual tradespeople without proper coordination leads to sequencing failures, delays, and disputes about who is responsible for defects.

Ask directly how subcontractors are selected, supervised, and managed.

10. Confirm a Single Point of Contact

On any well-managed project, you should have one named person accountable for delivery — a project manager or site manager who you can contact when questions arise, who attends progress reviews, and who communicates clearly about programme, progress, and any changes.

A contractor who cannot tell you who that person will be before work starts has not given enough thought to how your project will actually be run.

Red Flags: When to Walk Away

Stop and reconsider if you encounter any of the following:

• Cash-only payment demanded
• No written contract offered — or pressure to proceed on a handshake
• Pressure to start work immediately or to sign without time to review
• No fixed price offered for a clearly defined scope
• Inability to provide references or insurance certificates
• No clear answer on who manages subcontractors

Why RCB Design & Build Is the Safe Choice

RCB Design & Build is a full-service, FMB, TrustMark, Checkatrade, and TrustATrader-accredited principal contractor operating across Greater London. We cover everything from loft conversions and rear extensions to full house refurbishments and structural alteration programmes — with one team, one point of contact, and one accountable party from first call to project completion.

We don't just build. We manage the full process: design coordination, pre-construction planning, procurement, delivery, and formal handover. Everything is documented, everything is explained, and you always know where your project stands.

Ready to Get Started?

Call 07359 872594 or email contact@rcbgroup.co.uk

RCB Design & Build | A2Z Principal Contractors | rcbgroup.co.uk | FMB | TrustMark | Checkatrade | TrustATrader