Embarking on a home extension, loft conversion, or renovation is an exciting project, but it requires hiring the right construction professionals. Because general building is largely unregulated in the UK, anyone can buy a van, call themselves a builder, and start taking jobs.
To protect your home and your budget, you must carry out thorough vetting. In this guide, we break down step-by-step how to find a good builder, check their credentials, verify their insurance, and set up a solid contract.
1. Look for trade body memberships
Since there is no universal mandatory license for builders, reputable trade associations serve as a seal of quality. Always ask if your builder is registered with the following bodies:
- Federation of Master Builders (FMB): The FMB is the UK's largest construction trade association. To join, builders must pass a strict vetting process that includes financial checks, insurance verification, and independent on-site inspections of their work. FMB builders also offer dispute resolution services.
- TrustMark: This is the only government-endorsed quality scheme for home improvements. TrustMark registered builders are vetted for technical competence, trading practices, and customer service.
- NHBC (National House Building Council): If you are building a new-build home or a major extension, look for NHBC registration. This provides structural warranties (such as Buildmark) protecting you against structural defects for up to 10 years.
2. Check professional qualifications and safety cards
While formal credentials are not always mandatory, they show a commitment to craftsmanship:
- NVQs / SVQs in Construction: National Vocational Qualifications in bricklaying, carpentry, or site management indicate structured training.
- City & Guilds qualifications: Highly respected vocational training certificates in various building trades.
- CSCS Card (Construction Skills Certification Scheme): Shows the builder has passed the required health, safety, and environment tests to work on construction sites.
3. The essential vetting checklist
Before signing a contract or agreeing to start dates, check off these four steps:
- Verify Public Liability Insurance: Never hire a builder without insurance. Ask to see their certificate. A professional builder should have a minimum of £2 million to £5 million in Public Liability Insurance to cover accidental damage to your property or injury to individuals.
- Request recent references: Ask for contact details of two or three past clients who had similar work done within the last 12-18 months. Call them and ask: Was the builder on schedule? Did they stick to the budget? How did they handle issues or modifications? Did they keep the site tidy?
- Inspect previous work: Request photos of completed builds, or ask if you can visit a finished local project to inspect the brickwork, joint seals, and finishing details.
- Get three detailed, written quotes: Avoid vague estimates. A professional quote should detail materials, scaffolding, plant hire (e.g., skip or excavator), waste clearance, and labor. Avoid builders who submit extremely low quotes, as they may add hidden fees later or use substandard materials.
4. Protect your money with contracts and payment schedules
Never start a building project on a verbal agreement or handshake. A written contract protects both you and the builder:
- Use a standard homeowner contract: Formats such as the JCT Homeowner Contract or an FMB contract are legally sound and easy to understand.
- Link payments to milestones: Never pay a large sum (or the full balance) upfront. Agree on a payment schedule linked to completed milestones (e.g., 10% on setup, 20% when foundations are poured, 20% at joist level, etc.). Retain a final 5% to 10% until the work is fully signed off and snagging is complete.
- Agree on a timeline: The contract should specify a clear start date, expected milestones, and a final completion deadline, along with how delays (such as bad weather) will be managed.
Connect with vetted builders on GetBuilder
Finding a trustworthy local builder is easier when they are pre-screened. With GetBuilder, you can simplify your search:
- Post your job: Describe your project scope, budget, and location for free on GetBuilder.
- Vetted profiles: Get connected with local builders who are checked for insurance, previous reviews, and work quality.
- Safe hiring: Compare ratings, view portfolios, and manage your quotes safely with no upfront success fees.


