Questions to Ask Before Hiring a Builder
Hiring a builder for an extension, conversion, or structural work? These are the questions you need to ask before any contracts are signed or work begins.
Choosing the right builder is one of the most consequential decisions you can make as a homeowner. An extension, loft conversion, or structural renovation is a significant investment, and the difference between a good builder and a poor one can mean the difference between a successful project and months of stress, cost overruns, and remedial work.
Unlike electricians or gas engineers, builders in the UK are not regulated by a mandatory licensing scheme. This makes asking the right questions before you commit absolutely essential. Here is what you should be asking.
Before You Start: Getting the Right Quotes
Get at least three written quotes for any significant build project. Be specific about what you want so that each quote covers the same scope of work. Vague briefs produce vague quotes that are impossible to compare accurately.
A detailed quote should cover materials, labour, an estimated programme (timeline), what is excluded, and the payment schedule. If a builder cannot provide this, treat that as a signal about how they will run the project itself.
Key Questions to Ask Every Builder
Can I see examples of similar work you have completed recently?
Ask for photos and, ideally, the contact details of one or two past clients whose projects were similar to yours. A builder who is proud of their work will be happy to provide references. One who hedges or makes excuses is worth noting.
Are you a member of a trade body?
Membership of the Federation of Master Builders (FMB), TrustMark, or the Guild of Builders and Contractors is not a guarantee of quality, but it does mean the builder has passed a vetting process and is subject to a code of conduct and dispute resolution process. Check membership status directly on the relevant website.
Do you carry public liability insurance?
Builders working on your property must have public liability insurance. Ask for the policy details, including the insurer and the coverage amount. A minimum of £2 million is standard; for larger projects, £5 million or more is appropriate. Ask also whether they have employer's liability insurance if they bring subcontractors on site.
Who will be on site every day?
On larger projects, the person who quotes you may not be the person managing the day-to-day work. Ask who the site supervisor or foreman will be and whether you can meet them before work starts. A project without consistent, competent supervision is a project that drifts.
What is the programme?
Get a written timeline showing key milestones: when groundworks start, when the structure is at roof level, when fit-out begins, and the expected completion date. Ask how delays are handled and what happens if the project runs over programme due to the builder's own planning failures.
What is the payment schedule?
Never pay the full contract value upfront. Stage payments tied to completion milestones are standard and protect both parties. A typical structure might be: a small deposit to secure the start date, then payments at agreed stages (foundations complete, structure at first floor, roof on, fit-out complete, final snagging signed off). Be cautious of any builder who demands more than 10 to 20 per cent upfront.
What is included and excluded in the quote?
Ask specifically about:
- Demolition and site clearance
- Groundworks and foundations
- Supply and installation of all materials
- Electrical and plumbing first fix (if applicable)
- Plastering, rendering, and decorating
- Site security, welfare facilities, and waste removal
Anything that is excluded should be explicitly listed so you know what to budget for separately.
Do you use subcontractors, and if so, who are they?
Most builders use subcontractors for specialist trades like electrical work, plumbing, and roofing. Ask who they plan to use, whether those subcontractors are registered with the relevant schemes (Gas Safe, NICEIC), and who is responsible for managing and quality-checking their work.
How do you handle variations?
Changes to the original specification are almost inevitable on any significant build project. Ask how the builder handles change requests: will they provide a written variation order with revised costs before the work is done? This process keeps costs transparent and prevents disputes at the end of the project.
What warranties do you provide?
Ask about workmanship guarantees. Most reputable builders offer at least a 12-month defects period during which they will return to fix any issues that emerge. For structural work, consider whether a structural warranty (such as an NHBC Buildmark or similar) is appropriate.
Planning Permission and Building Regulations
Before any work starts, confirm who is responsible for obtaining planning permission and building regulations approval. On most projects, this is the client's responsibility, but many builders and architects can advise or manage the process. Do not let work begin until all necessary approvals are in place. If you do, you may be required to undo it.
Contracts
For any project above a few thousand pounds, a written contract is essential. The JCT (Joint Contracts Tribunal) publishes a Home Owner Contract that is widely used and available at low cost. It covers payment terms, dispute resolution, insurance, and programme. If a builder is reluctant to sign a contract, that reluctance itself tells you something.
Ready to Find a Builder?
Post your project on QuoteBank to get quotes from local builders who have been reviewed by homeowners. Describe the work, include any drawings or plans if you have them, and compare responses to find the right fit for your project.
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