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Summer 2026 is the ideal time for extensions. Dry weather and long days mean faster completion and fewer delays.
Get Extension QuotesA extension builder in the UK typically costs £15,000–£50,000 in 2026. TradeMatch connects homeowners with vetted, insured extension builder professionals across 200 UK locations. Post your job free, compare up to 5 quotes, and pay securely through escrow protection.
Single and double storey house extensions and side returns. Compare quotes from vetted extension builder professionals across the UK. Typical cost: £15,000–£50,000.

Quick answer
An extension builder handles groundwork, structure, roof and finishing for a single- or double-storey home extension. UK 2026 typical cost: £1,500–£2,500 per m² (London: +30–40%). A 4×5m single-storey rear runs £30,000–£60,000. Most need Building Regs approval; some need full planning permission. Allow 10–14 weeks for single, 14–20 for double.
| Job | Extension builder | General builder | Loft converter |
|---|---|---|---|
| Single-storey rear extension | ✅ Recommended | ⚠️ Variable quality | ❌ Out of scope |
| Double-storey side return | ✅ Recommended | ⚠️ Variable quality | ❌ Out of scope |
| Loft conversion | ⚠️ Some | ⚠️ Variable quality | ✅ Recommended |
| Garage conversion | ✅ Yes | ✅ Yes | ⚠️ Sometimes |
| Internal renovation | ⚠️ Possible | ✅ Recommended | ❌ Out of scope |
Use a builder who specialises in extensions for anything structural. A specialist coordinates planning, structural engineer, party-wall surveyor and Building Control on your behalf.
A extension builder provides single and double storey house extensions and side returns. Whether you need routine maintenance, emergency repairs, or a major installation project, a qualified extension builder has the skills, tools and experience to complete the work safely and to a high standard. On TradeMatch, every extension builder is vetted, background-checked, and holds verified public liability insurance — giving you peace of mind that your project is in safe hands.
When hiring a extension builder, always verify their qualifications. The following are the key credentials and trade body memberships regulated by Relevant trade association:
On TradeMatch, we verify all of these credentials before any extension builder can quote on jobs.
Every tradesperson is verified against the UK accreditation bodies that matter for the work — before they can quote.

Use this checklist before hiring a extension builder to ensure you get quality work at a fair price:
Watch out for these warning signs when getting quotes for extension builder work:
TradeMatch eliminates these risks — every extension builder is vetted, insured, and payments are escrow-protected.
You can hire a extension builder at any time of year, but planning ahead and booking during off-peak months (typically late autumn to early spring) can help you get better availability and potentially lower prices. For emergency work, TradeMatch has professionals available for same-day callouts.
Browse vetted extension builder professionals across 200 UK cities.
| Job | Low | Average | High |
|---|---|---|---|
| Small job | £80 | £200 | £400 |
| Medium job | £300 | £700 | £1,500 |
| Large job | £1,000 | £2,500 | £5,000 |
| Consultation/survey | £50 | £100 | £250 |
| Emergency callout | £80 | £150 | £300 |
Prices are estimated UK averages for 2026. Actual costs vary by location, materials and scope of work.
Rear, side and wrap-around single storey extensions under permitted development
£15,000–£40,000Two storey extension with planning application, structural design and full build
£30,000–£80,000Open-plan kitchen-diner extension with bi-fold doors and roof lantern
£20,000–£50,000Tell us what extension builder work you need — it only takes 2 minutes.
Receive up to 3 quotes from vetted extension builder professionals near you.
Compare reviews, choose the best quote, and leave a review when the job is done.
Browse questions from homeowners about hiring a extension builder, costs, and what to expect.
Side-by-side with the four most-searched UK trade platforms. No subscription fees, up to 5 competing quotes, escrow-protected payments — three things every other platform misses.
| Feature | TradeMatch | Checkatrade | MyBuilder | Bark | Rated People |
|---|---|---|---|---|---|
| Up to 5 quotes | ✓ | Browse | Up to 5 | Varies | Up to 3 |
| Escrow payment protection | ✓ | ✗ | ✗ | ✗ | ✗ |
| No tradesperson subscription | ✓ | £50+/mo | ✓ | Credits | £15+/mo |
| Verified reviews (live) | ✓ | 5-day delay | ✓ | Mixed | ✓ |
| Background + qualification checks | ✓ | ✓ | Light | Basic ID | ✓ |
| Dispute resolution team | ✓ | ✗ | ✗ | ✗ | ✗ |