Building

Expert advice on structural work, home extensions, renovations and understanding building regulations.

How to Choose a Builder for Your Extension: Questions Every Homeowner Should Ask

30th October 2025

Planning a home extension is exciting; it adds space, comfort, and value to your property. But choosing the right builder can make the difference between a smooth project and a stressful one. With so many contractors available, knowing what to ask before signing a contract is key. Here’s how to find a reliable builder and avoid common pitfalls.

Check experience and qualifications

Start by asking how much experience the builder has with extensions similar to yours. An experienced builder will understand planning permissions, building regulations, and structural requirements. Don’t hesitate to ask for evidence of qualifications or memberships in recognised bodies, and search for builders near you on Trust A Trader, where traders are vetted and reviewed by real customers.

Ask to see previous work

A reputable builder will be proud to show you examples of completed projects. Ask to see photos or, if possible, visit a current site to see the quality of their workmanship. Speaking with past clients can give valuable insight into how reliable, tidy, and communicative the builder is throughout the process; thoroughly reading reviews can also give you a great insight into how the builder operates and what you can expect from them.

Get multiple written quotes

Never rely on verbal estimates. Request at least three written quotes so you can compare like for like. Be wary of quotes that are significantly cheaper than others; this may mean corners will be cut or additional costs will appear later. A detailed quote should include materials, labour, timeframes, and any subcontractors involved (such as electricians or plumbers).

Clarify planning and permissions

Ask whether planning permission or building control approval is needed for your extension. While smaller extensions may fall under permitted development, it’s always best to confirm before the work starts, as failing to do so could result in expensive complications. A professional builder should be happy to guide you through the process or recommend a reliable architect or surveyor if needed.

Discuss timelines and payments

Agree on a realistic start and completion date and make sure payment terms are clear from the beginning. Avoid paying large sums in advance. Instead, stage payments tied to progress milestones keep both sides secure. Always get a written contract detailing the schedule, cost, and expectations.

Check insurance and warranties

Ensure your builder holds public liability insurance and, ideally, contract works insurance. This protects you and your property should something go wrong. Reputable builders often provide warranties on their work, giving you added peace of mind.

Choosing a builder for your extension is a major decision, but taking time to research and ask the right questions will pay off. By selecting a vetted professional through a trusted platform like Trust A Trader, you’ll ensure your project runs smoothly, stays on budget, and delivers the home you’ve been dreaming of. Got any questions? Get in touch on Facebook or X.

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Find clear, practical answers to common building questions, helping homeowners understand everyday issues, know what checks they can carry out safely, and when it is best to contact a qualified professional.

Do I need planning permission for a home extension?

Plenty of extensions don't need planning permission - they fall under Permitted Development. Whether yours qualifies depends on the size, location, and type of build. Single-storey rear extensions up to four metres on a detached house often get the green light, but side extensions, two-storey builds, and properties in conservation areas usually do need permission. Always check with your local planning authority before you start - building without the right approvals can mean being made to undo it all.
What is involved in building a conservatory?

You're looking at groundworks and foundations, the frame and glazing, the roof, and then the internal fit-out - flooring, heating, electrics. Most conservatories under a certain size fall under Permitted Development, but they still need to comply with Building Regulations, especially if you want to use the space as a proper room year-round. On the roof: solid or tiled options make a huge difference to usability - traditional polycarbonate can be unbearably hot in summer and freezing in winter. Most projects take two to six weeks.
Do I need a structural engineer for my home renovation?

Not for everything - but if structural changes are involved, yes. Removing a load-bearing wall, putting in a steel beam, touching the roof structure, or adding a sizeable extension all need a structural engineer to design the solution and produce the calculations for Building Regulations approval. A builder might tell you whether a wall is load-bearing, but only a structural engineer can specify the right beam and carry professional liability for that advice.
Do I need planning permission to install patio doors?

Usually not, if you're replacing an existing door or window in the same opening - that typically falls under Permitted Development. But if you're making the opening larger or creating a new one in an external wall, you may need planning permission or Building Regulations approval. Conservation areas, listed buildings, and properties with an Article 4 Direction have tighter rules, so check before assuming. Any structural work to the opening, like fitting a new lintel, needs Building Regs sign-off regardless.
Does my extension need Building Regulations approval even without planning permission?

Almost always, yes. Planning permission and Building Regulations are two separate things. Extensions need to meet regulations covering structural integrity, fire safety, insulation, ventilation, and drainage - regardless of whether you needed planning approval. Your local authority's building control team can confirm exactly what's required. And don't skip it - missing Building Regs sign-off can cause real headaches when you come to sell.
How long does a typical home extension take?

A small single-storey extension usually takes eight to twelve weeks from groundworks to completion. Add several months if planning permission is needed before work can even begin. Bigger builds - two-storey additions or anything needing significant structural work - can take four to six months or more. Get a realistic timeline from your builder upfront, and factor in a buffer for the unexpected.

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