Are you starting to feel like your home is bursting at the seams? Maybe your kitchen table has become a makeshift office, the kids are outgrowing their shared bedroom, or you simply dream of a bigger living space that actually fits your lifestyle. If you're a homeowner in Bournemouth, Poole, or Christchurch, a single-storey extension could be the smartest investment you make this year.
But here's the thing , before you start picturing that light-filled kitchen-diner or spacious home office, you probably have some burning questions. How much will it actually cost? How long will it take? And how do you avoid those nightmare stories about budgets spiralling out of control?
This guide gives you the straight answers. No fluff, no sales jargon , just the practical information you need to plan your single-storey extension with confidence.
What Does a Single-Storey Extension Cost in Bournemouth?
Let's start with the numbers, because that's what most people want to know first.
For a single-storey extension in the Bournemouth area, you're typically looking at £1,500 to £3,000 per square metre. Most projects in our region fall between £2,200 and £3,300 per square metre, depending on the specification and complexity of your build.
To put that into real terms:
| Extension Size | Estimated Cost Range |
|---|---|
| 20m² | £30,000 – £60,000 |
| 25m² | £60,000 – £85,000 |
| 30m² | £66,000 – £99,000 |
These figures exclude VAT and professional fees, but they give you a solid starting point for your planning.
What Makes the Price Vary?
You might be wondering why there's such a wide range. It comes down to a few key factors:
Design complexity , A straightforward rectangular extension with a flat roof costs less than a design with multiple corners, pitched roofing, or structural glazing.
Material quality , Standard materials and finishes sit at the lower end of the scale. If you're dreaming of bi-fold doors, underfloor heating, or a high-spec kitchen fit-out, expect to move towards the upper end.
Ground conditions , Here in Bournemouth, soil types can vary significantly. Some sites need more extensive foundations, which adds to the cost.
Access , If your property has tricky access for deliveries and skip placement, this can affect labour costs.
The good news? A reputable local builder will assess all of these factors upfront, so you know exactly what you're paying for before work begins.
Your Extension Timeline: What to Expect Week by Week
One of the biggest concerns homeowners have is disruption. How long will builders be on site? When can you actually use your new space?
Here's a realistic timeline for a typical single-storey extension in Bournemouth:
Weeks 1-2: Groundwork and Foundations
This is where it all starts. The team excavates, lays foundations, and installs drainage. It's the messiest phase, but it's also the most critical , get the foundations right, and everything else follows smoothly.
Weeks 3-5: Structural Build
Walls go up, the roof structure takes shape, and your extension starts to look like an actual room. By the end of this phase, you'll see the footprint of your new space and get genuinely excited.
Weeks 6-8: Weatherproofing and First Fix
Windows and doors are fitted, making the space watertight. Electricians and plumbers complete the "first fix" , running cables, pipes, and heating systems before the walls are finished.
Weeks 9-10: Plastering and Second Fix
Internal walls are plastered and dried. Then comes the second fix: sockets, switches, radiators, and bathroom fittings all go in.
Weeks 11-12: Decoration and Completion
Painting, flooring, skirting boards, and final finishes. Your builder completes snagging, and you get the keys to your brand-new space.
Total typical build time: 10-14 weeks (depending on size and complexity).
Of course, every project is different. A smaller 15m² extension might take 8 weeks, while a larger 35m² build with a complex design could stretch to 16 weeks. The key is getting a clear timeline from your builder before you commit.
Ready to find out how long your project would take? Get in touch with The Big Conversion Company for a free, no-obligation feasibility chat.
How Fixed-Price Quoting Works (And Why It Matters)
Here's a scenario you've probably heard before: a friend starts an extension with a quoted price of £50,000, and six months later they've spent £75,000. Hidden extras, unexpected costs, "we didn't account for that" , it's stressful, expensive, and unfortunately common.
That's exactly why fixed-price quoting exists.
What Is a Fixed-Price Quote?
A fixed-price quote means the price you're given at the start is the price you pay at the end. Full stop. No surprise invoices, no "we need another £3,000 for the foundations" conversations, no budget anxiety.
How Do We Make It Work?
At The Big Conversion Company, we follow a thorough process to ensure our fixed-price quotes are accurate and fair:
1. Detailed Site Survey
We visit your property, assess the existing structure, check access, and discuss exactly what you want to achieve. No guesswork.
2. Full Specification Document
Before quoting, we create a detailed specification covering every element: materials, fixtures, finishes, and allowances. You know precisely what's included.
3. Contingency Built In
We factor in realistic contingencies for the unexpected , because in construction, surprises happen. But they're our problem to manage, not yours.
4. Transparent Breakdown
You receive a clear, itemised quote showing where every pound goes. No vague "labour and materials" line items.
5. Written Guarantee
The fixed price is locked in contractually. If costs increase due to something we should have anticipated, we absorb it.
This approach takes more work upfront, but it means you can plan your finances with complete confidence.
Want a fixed-price quote for your extension? Book a free site survey today and we'll show you exactly what's possible within your budget.
Stress-Free Project Management: What It Actually Looks Like
Beyond the money, most homeowners worry about the hassle. Will you need to take time off work to let trades in? Will different contractors blame each other when things go wrong? Will you spend your evenings chasing updates?
When you work with a full-service extension company, the answer to all of these is no.
One Point of Contact
You deal with one project manager throughout. They coordinate every trade, handle scheduling, and keep you updated. No chasing plumbers or arguing with electricians.
Realistic Scheduling
We plan the project properly from day one, booking trades in advance and building in buffer time. That's how we deliver on time : not by making promises we can't keep.
Clear Communication
You'll know what's happening each week, what's coming next, and whether we're on track. If anything changes, you hear about it immediately : not when it's too late to adjust.
On-Time Completion
We understand that your life revolves around deadlines. Maybe you're hosting Christmas in the new space, or the baby's due in September, or you've already sold your old furniture. Whatever your deadline, we plan backwards from it and make it happen.
Is a Single-Storey Extension Right for You?
A single-storey extension isn't just about adding square footage. It's about transforming how you live : creating space for your family to grow, work, and relax without the upheaval and cost of moving house.
If you're in Bournemouth, Poole, or Christchurch, you're in the right place. We know the local planning requirements, the soil conditions, the architectural styles that work : and we've built extensions for dozens of families just like yours.
Your Next Step
Stop guessing and start planning. Whether you're at the daydreaming stage or ready to break ground, a quick conversation can clarify your options, your budget, and your timeline.
Contact The Big Conversion Company today for a free, no-obligation chat about your single-storey extension. We'll visit your property, discuss your ideas, and give you a fixed-price quote you can actually rely on.
No pressure. No hard sell. Just honest advice from a local team that's built its reputation on delivering what we promise.
Planning an extension in Bournemouth, Poole, or Christchurch? Browse more home renovation guides or get in touch to discuss your project.