Building work — extensions, renovations, structural alterations — is among the largest financial commitments most households ever make. It is also one of the most common sources of consumer disputes in the UK. Knowing how to verify a builder before signing a contract can save you from financial loss, legal battles, and unsafe buildings.
Check Companies House first
If a builder operates as a limited company, their details are public at companieshouse.gov.uk. Look for: the company's registered address, director details, how long it has been trading, and whether accounts have been filed regularly. A company that has been dormant for years and suddenly become active, or one with a very recent incorporation date, deserves closer scrutiny.
Rogue traders sometimes dissolve companies after disputes and register new ones. If a builder's company has been dissolved and reformed more than once, this is a significant red flag.
Look for Federation of Master Builders (FMB) membership
The Federation of Master Builders is the UK's largest trade association for small and medium-sized building companies. Members must pass an independent inspection, carry public liability insurance, and adhere to a code of practice. In the event of a dispute, the FMB offers a free dispute resolution service.
You can verify membership at fmb.org.uk. The FMB also offers an insurance-backed warranty scheme for member work.
TrustMark — the government-endorsed quality scheme
TrustMark is a government-endorsed scheme covering a wide range of trade businesses including builders. TrustMark businesses have been assessed for technical competence, trading practices, and customer service. Search the register at trustmark.org.uk.
Protect your money with a proper contract
Never begin significant building work without a written contract. The JCT (Joint Contracts Tribunal) publishes consumer-friendly home building contracts. At minimum, the contract should specify:
- A detailed scope of work and specification
- A payment schedule tied to progress milestones (not time)
- A start date and estimated completion date
- What happens if the specification changes (variation orders)
- Retention: holding back 5–10% until a snagging period is complete
Understanding deposit protection
A reasonable deposit for building work is 10–25% of the total contract value. If a builder asks for more than 30% upfront, ask why. For very large contracts, consider using a deposit protection scheme — some FMB members offer these.
Check planning and building regulations requirements
Many building projects require planning permission and/or building regulations approval. A legitimate builder will tell you what is required and help you obtain it. A builder who says "you don't need planning for this" for anything structural or significant should be treated with caution — this is your legal responsibility, not theirs, and ignorance is not a defence.
Questions to ask before hiring
- Can I see your public liability and employer's liability insurance certificates?
- Are you FMB, TrustMark, or LABC warranty registered?
- Can you provide three references for similar projects completed in the last 12 months?
- Will you provide a detailed written specification and contract before work starts?
- How will you handle building regulations approval for this project?