How to Choose a Builder in Hertfordshire: What to Check Before You Sign

Word-of-mouth recommendations are a reasonable starting point, but they are not sufficient on their own. A builder who did a good job for your neighbour's kitchen extension may not have the structural engineering capability, the insurance coverage, or the project management experience for a double-storey extension or a commercial fit-out. Recommendations tell you about past performance on a specific type of project — they do not tell you about the builder's capacity for your project.

The first check is company registration. Any contractor working on projects above a certain scale should be operating as a limited company or a registered sole trader. You can verify a company's registration, filing history, and director details on Companies House (companies-house.service.gov.uk) in under two minutes. A company that has been incorporated for less than a year, has no filed accounts, or has a history of dissolved companies under the same director's name is a significant warning sign.

TCM Building & Maintenance Ltd was incorporated on 19 May 2014 and has been trading continuously since. Our Companies House record is publicly available and shows a consistent trading history. That kind of verifiable track record is the baseline you should expect from any contractor you are seriously considering.

Contractor insurance is not optional — it is the single most important document to request before any work begins. There are three types of insurance that a reputable building contractor should carry as a minimum.

Public liability insurance covers damage to your property or injury to third parties caused by the contractor's work. The minimum level for domestic building work is £1 million, though £2 million or £5 million is more appropriate for larger projects. Employers' liability insurance is a legal requirement for any contractor who employs workers. It covers injury or illness suffered by employees in the course of their work on your site. Without it, you as the homeowner may be exposed to liability if a worker is injured. Contract works insurance (also called all-risks insurance) covers the works themselves against damage during construction — fire, flood, theft of materials, and accidental damage.

Ask for a copy of the contractor's insurance certificates before you sign anything. A reputable contractor will provide these without hesitation. Verify that the policies are current — check the expiry date on the certificate, not just the policy number. If a contractor is reluctant to provide insurance documentation, treat that as a decisive reason not to proceed.

Three quotes is the standard advice, and it is good advice — but only if the quotes are genuinely comparable. A quote that is significantly lower than the others is not necessarily better value. It may reflect a lower specification, excluded items, or a contractor who intends to recover the margin through variations once work has started.

To get comparable quotes, provide every contractor with the same written brief. This should include the scope of work, the specification of materials and finishes, the programme requirements, and any specific conditions (access restrictions, working hours, protection of existing finishes). When you receive the quotes, check that each one covers the same scope. Items that are excluded from one quote but included in another will make the comparison misleading.

Pay particular attention to what is excluded. A quote that excludes building regulations fees, structural engineer's calculations, skip hire, or making good after trades will be lower on paper but higher in practice. Ask each contractor to confirm in writing that their quote is inclusive of all costs required to complete the project to a finished standard, and that any exclusions are explicitly listed.

The lowest quote is rarely the best choice. The question to ask is not "which is cheapest?" but "which contractor gives me the most confidence that this project will be completed to the standard I expect, on time, within the quoted budget?"

References from previous clients are a standard part of the vetting process, but the way most homeowners use them is too passive to be genuinely useful. Calling a reference and asking "were you happy with the work?" will almost always produce a positive answer — contractors only provide references from clients they know are satisfied.

More useful questions to ask a reference: Did the project finish on time? If not, by how long did it overrun, and what was the reason? Did the final cost match the quoted cost? If not, what caused the difference? Were there any defects after completion, and how quickly were they rectified? Would you use this contractor again for a larger project?

If the contractor has a Checkatrade profile, read the reviews in full rather than just looking at the overall score. Checkatrade verifies that reviews are from genuine customers who have used the contractor. Look at the pattern of reviews over time — a contractor with consistently high scores over several years is more reliable than one with a cluster of recent five-star reviews and a gap before that.

TCM Building & Maintenance has been on Checkatrade since our early years of trading. Our profile at checkatrade.com/trades/tcmbuildingandmaintenancelimited shows verified reviews from clients across Hertfordshire and North London, covering a range of project types and sizes.

A written contract is not bureaucracy — it is the document that protects both parties if a dispute arises. The contract should be signed before any work begins and before any deposit is paid. At a minimum, it should include the scope of works in sufficient detail to identify what is and is not included; the contract price, including a clear statement of what is fixed and what may vary; the payment schedule, tied to defined stages of completion rather than to dates; the programme, with a start date and a target completion date; the process for agreeing variations to the scope or price; the defects liability period, during which the contractor is responsible for rectifying defects at no additional cost; and the dispute resolution process.

The JCT (Joint Contracts Tribunal) produces standard form contracts for domestic building work that are widely used and well understood by both contractors and solicitors. The JCT Minor Works Building Contract and the JCT Homeowner Contract are both appropriate for domestic extension and renovation projects. Using a standard form contract reduces the risk of ambiguity and provides a clear framework for managing any issues that arise during the project.

The payment schedule is one of the most important elements of the contract, and one of the most common sources of disputes. The principle is straightforward: payments should be tied to completed stages of work, not to dates or to the contractor's cash flow requirements.

A typical payment schedule for a house extension might look like this: 10% deposit on contract signing; 20% on completion of foundations and ground-floor slab; 20% on completion of structural frame and roof; 20% on completion of first fix (electrical, plumbing, partitions); 20% on completion of second fix and plastering; 10% on practical completion and sign-off. This structure ensures that the contractor is always working slightly ahead of payment, which protects you against a contractor who takes payment and then slows down or abandons the project.

Never pay more than 10–15% upfront, regardless of what the contractor requests. If a contractor cannot fund the initial materials purchase from their own working capital or a trade account, that is a sign of financial instability that will create problems throughout the project.

Trade body memberships and accreditations are not a guarantee of quality, but they do provide a level of accountability that unregistered contractors lack. The Federation of Master Builders (FMB) requires members to pass a quality assessment and provides a dispute resolution service. TrustMark is a government-endorsed quality scheme that covers a range of trades. Checkatrade vets contractors and verifies that reviews are from genuine customers.

For specific types of work, look for relevant accreditations. Electrical work should be carried out by a contractor registered with NICEIC or NAPIT, which allows them to self-certify their work under Part P of the Building Regulations. Gas work must be carried out by a Gas Safe registered engineer. Structural work on a project requiring building regulations approval will be inspected by the local authority building control or an approved inspector — the contractor should be familiar with this process and have a track record of successful sign-offs.

The quality of a contractor's pre-construction process tells you a great deal about how they will manage the build itself. A contractor who arrives for the initial survey without a notepad, who gives you a verbal quote on the spot without measuring anything, and who cannot answer specific questions about the construction method is not one who will manage your project with the rigour it requires.

A good contractor will conduct a thorough survey, ask detailed questions about your requirements and priorities, and take time to understand the specific constraints of your property. They will follow up with a written quote that breaks down the costs by trade and clearly states what is included and excluded. They will be able to explain the construction sequence, the likely programme, and the key risks that might affect the timeline or cost.

At TCM, our initial site visits typically take 45–90 minutes depending on the complexity of the project. We bring a structural engineer on visits where structural work is anticipated. We follow up with a written quote within five working days, broken down by trade and stage, with a clear statement of inclusions and exclusions. That level of detail at the quote stage is what allows us to deliver projects on budget — because we have understood the scope properly before we price it.