How to Choose a Builder in Hertfordshire: A Practical Vetting Guide

The building industry in England is largely unregulated. Anyone can call themselves a builder, take a deposit, and start work — there's no mandatory licensing, no minimum qualification requirement, and no central register of competent contractors. That's not a criticism of the industry; it's a fact that shapes how you need to approach the selection process.

A trustworthy builder has three things: a verifiable legal identity, adequate insurance, and a track record of completed work you can inspect or verify. Everything else — accreditations, memberships, website quality, van livery — is secondary. The vetting process described in this guide is designed to confirm all three before you sign anything.

According to the Federation of Master Builders' (FMB) State of Trade Survey 2024, 40% of homeowners who experienced problems with a building project said they had not checked the contractor's insurance before appointing them. That single omission accounts for a disproportionate share of the disputes that end up in court or with the Citizens Advice Bureau.

Before you ask for a quote, check that the company exists as a legal entity. Go to Companies House (companieshouse.gov.uk) and search for the company name. A legitimate limited company will have a registration number, a registered address, filed accounts, and a list of directors. Check when the company was incorporated — a company registered last month with no filed accounts is a different proposition to one that has been trading for ten years with clean accounts.

For sole traders, ask for a UTR (Unique Taxpayer Reference) number and verify they are registered for Self Assessment with HMRC. This is a basic indicator of legitimacy. Also check the Insolvency Register at gov.uk to confirm the company or individual has no active insolvency proceedings.

TCM Building & Maintenance Ltd was incorporated on 19 May 2014 (Company Number: 09044688) and has filed accounts consistently since incorporation. That's the kind of verifiable trading history you should be looking for.

Three insurance policies are non-negotiable for any building contractor working on your home.

Public Liability Insurance covers damage to your property or injury to third parties caused by the contractor's work. The minimum acceptable level for residential building work is £2 million; most reputable contractors carry £5 million or more. Ask for the certificate — not just a verbal confirmation — and check the expiry date and the name of the insured entity (it must match the company you're appointing).

Employers' Liability Insurance is a legal requirement for any contractor who employs staff. It covers injury to employees during the course of their work. The minimum legal level is £5 million. If a contractor's employee is injured on your property and the contractor doesn't have employers' liability insurance, you may face a claim.

Contract Works Insurance (also called All Risks or Contractors' All Risks) covers the works themselves — the materials and partially completed structure — against damage, theft, and fire during the build. Without it, if a fire destroys a partially built extension, the loss falls on whoever doesn't have insurance. Always confirm this is in place before work starts.

Three quotes is the standard recommendation, but the quotes are only comparable if they're based on the same specification. Before approaching contractors, prepare a written brief that specifies: the scope of work, the materials and finishes you want (or ask each contractor to specify what they're pricing), the programme you need, and any specific requirements (e.g., working around school holidays, protecting a particular tree, matching existing brickwork).

When you receive the quotes, compare them line by line. A quote that's 30% cheaper than the other two is almost always cheaper because it's missing something — either scope, quality of materials, or the cost of items the contractor expects to charge as extras later. The FMB recommends treating any quote that's more than 20% below the median as a warning sign requiring explanation.

Ask each contractor to break down their quote into: groundworks and foundations, structural frame, external envelope (walls, roof, windows), internal fit-out, and preliminaries (site setup, skips, scaffolding). This breakdown makes it much easier to identify where the differences lie.

Experience teaches you to recognise the warning signs early. Here are the seven most reliable indicators that a contractor is not the right choice for your project.

1. Requests a large upfront deposit. A legitimate contractor with a healthy cash flow does not need 30–50% of the contract value before work starts. A reasonable deposit for a residential project is 10–15%, with staged payments tied to programme milestones. Requests for large upfront payments are the single most common precursor to contractor fraud.

2. Cannot provide insurance certificates. If a contractor says their insurer will send the certificate "next week" or offers a verbal assurance instead, walk away. Insurance certificates are issued immediately upon policy inception and should be available on request within 24 hours.

3. Pressures you to decide quickly. "I've got a gap in my schedule next week but I need to know by tomorrow" is a sales technique, not a genuine scheduling constraint. A contractor who pressures you to sign before you've had time to check references and compare quotes is not operating in your interest.

4. Suggests avoiding VAT by paying cash. This is tax evasion. If a contractor suggests it, they're asking you to participate in an illegal arrangement — and if HMRC investigates, you may face consequences too. It also means the contractor has no incentive to provide a paper trail for the work, which makes disputes much harder to resolve.

5. Cannot show you completed projects. Every experienced contractor has a portfolio of completed work they're proud of. If a contractor can't show you at least three completed projects — ideally with contact details for the clients — that's a significant gap.

6. No written contract. Any project over £1,000 should have a written contract. For a house extension or loft conversion, a JCT Minor Works Building Contract is the industry standard. A contractor who refuses to use a written contract, or who offers only a one-page "quote and acceptance" document, is not protecting your interests.

7. Vague about subcontractors. Most builders use subcontractors for specialist trades — groundworks, steelwork, roofing, electrical, plumbing. That's normal and fine. What matters is whether the main contractor takes responsibility for the subcontractors' work and whether those subcontractors are also insured. Ask directly: "Who will be carrying out the structural work, and are they covered by your insurance?"

The JCT Minor Works Building Contract is the standard form for residential building projects in England. It covers the scope of work, the contract sum, the programme, the payment schedule, variations, defects liability, and dispute resolution. It's available from the Joint Contracts Tribunal (jctltd.co.uk) for approximately £50 and is worth every penny.

The payment schedule should be tied to programme milestones, not calendar dates. Milestone-based payments — for example, 15% on completion of foundations, 25% on completion of the structural frame, 25% on completion of the external envelope — give you leverage throughout the project. If work stalls, you haven't paid for work that hasn't happened.

Retain 5% of the contract sum as a defects retention, released 6–12 months after practical completion. This gives the contractor an incentive to return and fix any defects that emerge after handover, and gives you a financial remedy if they don't.

Several industry accreditations provide a meaningful baseline of quality assurance. The Federation of Master Builders (FMB) requires members to pass an independent inspection of their work and carry adequate insurance. The Checkatrade platform verifies contractor identity, insurance, and qualifications, and publishes customer reviews that cannot be edited by the contractor. The TrustMark scheme is government-endorsed and requires contractors to meet standards for technical competence, customer service, and trading practices.

None of these accreditations are a substitute for your own due diligence — they're a starting point, not an endpoint. But a contractor who holds multiple accreditations and has a strong review profile across several platforms has demonstrated a consistent commitment to quality that carries real weight.

TCM Building & Maintenance Ltd has been trading since 19 May 2014 (Companies House number 09044688). We carry £5 million public liability insurance, £10 million employers' liability insurance, and contract works insurance on every project. Our insurance certificates are available on request before any contract is signed.

We use JCT Minor Works contracts as standard for all residential projects over £10,000. Our payment schedules are milestone-based, with a 5% defects retention released 12 months after practical completion. We don't ask for large upfront deposits — our standard deposit is 10% of the contract sum, with staged payments tied to programme milestones.

Our Checkatrade profile shows independently verified reviews from clients across Borehamwood, Radlett, Watford, Barnet, and the wider Hertfordshire area. Our team includes structural engineers, architects, and interior designers who work together from initial feasibility through to final handover — which means you have one point of contact for the entire project, not a main contractor who disappears when the subcontractors arrive.

If you're currently comparing builders for a project in Hertfordshire, we're happy to walk you through our insurance certificates, our contract form, and our programme methodology before you make any commitment. That's the kind of transparency you should expect from any contractor you're considering.