What to look for in a builder
- CSCS card — The Construction Skills Certification Scheme card proves a builder has passed a health-and-safety test and holds a recognised construction qualification. It is not legally required for all work, but a reputable builder will carry one.
- Federation of Master Builders (FMB) membership — FMB members are independently vetted, carry insurance, and agree to a code of practice. Their work is also covered by a warranty scheme. It is one of the strongest signals of a professional builder.
- Public liability insurance (minimum £5 million) — Building work carries higher risk than most trades. Structural failures, scaffold collapses, and accidental damage to neighbouring properties all happen. Insist on seeing the certificate and check the policy is current.
- Planning and Building Regulations knowledge — A competent builder will know whether your project needs planning permission, Building Regulations approval, or a Party Wall Agreement. They should advise you proactively — not wait until enforcement notices arrive.
- References from comparable projects — Ask for references from jobs of similar size and type. A builder who has done loft conversions is not automatically suited to extensions or underpinning. Visit a completed project if possible.
- Written contract with payment schedule — A professional builder will use a written contract (JCT Minor Works or similar) with clear payment stages linked to milestones, not calendar dates.
Questions to ask before hiring
- Can I visit a recently completed project similar to mine? Seeing finished work tells you more than any website photo. Look at the quality of finishes, how junctions are handled, and whether the site was left clean.
- Who will be on site day-to-day, and who is the project manager? On larger jobs, the person you meet for the quote may not be the one doing the work. Find out who your daily point of contact will be and whether subcontractors are involved.
- What is the payment schedule, and is it milestone-based? Legitimate builders tie payments to completed stages: foundations, walls to plate height, roof, first fix, second fix, snagging. Never agree to large payments in advance of work being done.
- How do you handle variations and additional costs? Changes during a build are inevitable. Ask how they document variations, whether there is a day rate for extras, and how approvals work. Get this in the contract.
- Will you handle Building Regulations submissions? The builder should either submit plans themselves or coordinate with your architect. Ask whether they have a relationship with the local Building Control team and how inspections will be booked.
Red flags to watch for
- No written contract. A handshake deal on a building project is a recipe for disputes. Any builder who resists putting the scope, price, and timeline in writing should be avoided.
- Unusually low quote. If one quote is 30%+ below the others, the builder may be planning to use cheaper materials, underpay subcontractors, or add extras later. Understand exactly what is and is not included.
- Requests full payment upfront. A maximum of 10–15% as a deposit is normal. Any builder demanding full or majority payment before starting work is a serious risk.
- Cannot name subcontractors. If the builder says they will bring in specialists (electricians, plumbers, roofers) but cannot tell you who they are, they may be hiring the cheapest option on the day.
- No evidence of insurance. Building work can go wrong in expensive ways. A builder without public liability and employer’s liability insurance leaves you exposed to significant financial risk.
What to expect on costs
Builder costs vary enormously by project. A single-storey extension typically ranges from £30,000–£60,000 depending on size and finish. Loft conversions run £25,000–£50,000 for a dormer. Structural alterations such as removing a load-bearing wall might cost £2,000–£5,000 including the steel beam and making good.
For a detailed breakdown, see our full cost guide.
Find rated builders in Kent
- Builders in Kent — county-level directory
- Builders in Maidstone
- Builders in Canterbury
- Builders in Dartford
- Builders in Tunbridge Wells
- Builders in Ashford
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