You've decided to extend your home. Maybe you need a bigger kitchen, an extra bedroom, or a dedicated home office. Whatever the reason, you're about to make one of the biggest financial decisions of your life : and choosing the wrong builder could turn your dream project into a nightmare.
Here's the thing: in Bournemouth, Poole, and Christchurch, there are dozens of extension builders all promising the same things. Great results. On-time delivery. Competitive prices. But how do you separate the professionals from the cowboys?
The answer is simple: ask the right questions before you sign anything.
This checklist gives you 12 essential questions to ask any extension builder. We'll cover what good answers look like, the red flags to watch for, and how to protect yourself from budget blowouts, delays, and shoddy workmanship.
Why These Questions Matter
A house extension is a significant investment : often £30,000 to £100,000+ depending on the scope. Yet many homeowners sign contracts after just one meeting and a handshake. They don't ask the tough questions. They don't get things in writing. And when problems arise, they have no leg to stand on.
Don't be that homeowner.
The difference between a stressful build and a smooth one almost always comes down to clear paperwork and open communication from day one.
The 12 Questions You Must Ask
1. Can you show me recent local projects similar to mine?
Any reputable extension builder in Bournemouth should have a portfolio of completed work in the area. Ask to see projects that match your extension type and scale : whether that's a single-storey rear extension, a two-storey side return, or a wraparound kitchen-diner.
What good looks like: Photos, testimonials, and ideally the option to visit a completed project or speak to a previous client.
Red flag: Vague answers like "we've done loads" without any evidence to back it up.
2. Who will manage the job day-to-day, and how will they communicate with me?
This is crucial. You need to know who your main point of contact will be throughout the build. Will it be the company owner? A dedicated project manager? Or will you be chasing different tradespeople every day?
What good looks like: A named project manager with a clear communication plan : whether that's weekly site meetings, a WhatsApp group, or a project management app.
Red flag: No clear answer, or "just call the office if you need anything."
3. Can you provide a written scope that lists both inclusions AND exclusions?
This is where many homeowners get caught out. A quote might say "full extension build : £45,000" but what does that actually include? Foundations? Electrics? Plastering? Decoration?
What good looks like: A detailed written scope that lists exactly what's included : and just as importantly, what's not included.
Red flag: A one-page quote with no breakdown, or a builder who seems reluctant to put things in writing.
Pro tip: At The Big Conversion Company, we provide a fixed-price guarantee with a full written scope. No hidden extras. No nasty surprises. Book a free consultation to see how we work.
4. How are variations handled if changes arise during construction?
Even with the best planning, changes happen. Maybe you decide mid-build that you want bi-fold doors instead of French doors. Maybe structural issues are discovered during groundworks. You need to know how these variations will be handled and priced.
What good looks like: A clear variation process with written change orders and agreed costs before any additional work starts.
Red flag: "We'll sort it out as we go" or no formal process for managing changes.
5. What is the complete payment schedule, and how is it linked to project milestones?
Never pay a large deposit upfront before any work has started. A fair payment schedule should be linked to specific stages of the build : not arbitrary dates.
What good looks like: Stage payments tied to milestones (e.g., 10% on signing, 20% on foundations complete, 25% on roof on, etc.).
Red flag: Requests for 50%+ upfront, or payment demands that aren't linked to completed work.
6. What is the realistic start date and project duration?
Good builders are busy : but they should still be able to give you a realistic timeline. Push for specific dates, not vague estimates.
What good looks like: A clear start date with a week-by-week schedule showing key milestones.
Red flag: "We'll fit you in when we can" or constantly shifting start dates before the project even begins.
7. Who handles planning permission and building regulations approval?
Depending on your extension, you may need planning permission, and you'll almost certainly need building regulations approval. Bournemouth has specific permitted development rights that may affect your project.
What good looks like: The builder can explain exactly what approvals are needed and will coordinate with the local authority and building control on your behalf.
Red flag: "That's your responsibility" or confusion about what's required.
Not sure what permissions you need? Our team handles all the paperwork for you. Get in touch for a free feasibility check.
8. What are the material and finish specifications?
"Kitchen extension with tiled floor" isn't a specification. What tiles? What size? What brand? The devil is in the detail, and vague specs lead to disputes.
What good looks like: Detailed written specifications for all materials, finishes, fixtures, and fittings : with brands, model numbers, and colours where applicable.
Red flag: Reluctance to commit to specifics, or phrases like "standard quality materials."
9. Are you and your subcontractors properly accredited?
Your builder should be able to demonstrate relevant accreditations. Any electricians should be Part P registered. Gas engineers must be Gas Safe registered. Window fitters should be FENSA certified.
What good looks like: Certificates and registration numbers provided without hesitation.
Red flag: Defensive responses or claims that "we don't need that."
10. What insurance do you have, and what warranties do you offer?
At minimum, your builder should have public liability insurance (typically £2-5 million). They should also be clear about warranty periods for their workmanship and any manufacturer warranties on materials.
What good looks like: Copies of insurance certificates and a clear written warranty (typically 12-24 months on workmanship).
Red flag: No insurance, expired policies, or no warranty offered.
11. What is your snagging process and completion sign-off?
Snagging is the process of identifying and fixing minor defects after the main build is complete. A good builder will have a formal snagging process and won't expect final payment until everything is resolved.
What good looks like: A structured snagging walk-through with a written list, agreed timelines for fixes, and a formal sign-off process.
Red flag: "We'll pop back if there are any problems" with no formal process.
12. How do you maintain site safety, security, and cleanliness?
An extension build will disrupt your life for weeks or months. You need to know how the builder will manage the site to minimise that disruption.
What good looks like: Clear plans for site security, waste removal, dust control, and considerate working hours. Bonus points for regular site tidying.
Red flag: "It's a building site, what do you expect?" attitude.
What Happens If You Don't Ask These Questions?
We've seen it too many times. Homeowners who signed contracts without asking the right questions end up dealing with:
- Budget blowouts from "unforeseen" extras
- Projects that drag on for months past the agreed completion date
- Poor quality work that needs fixing at additional cost
- Communication breakdowns and stress
Asking these 12 questions won't guarantee a perfect build : but it will dramatically reduce your risk of problems.
Ready to Talk to a Builder Who Welcomes These Questions?
At The Big Conversion Company, we're happy to answer every single one of these questions in detail. We offer fixed-price guarantees, dedicated project management, and a transparent approach that puts you in control.
If you're planning a house extension or loft conversion in Bournemouth, Poole, or Christchurch, we'd love to chat.
Book your free consultation today : no obligation, no pressure. Just honest advice from local extension specialists who know what they're doing.