Flat roof extensions in Yeovil: design, approvals and build
From the first sketch to final sign-off, we plan and build flat roof extensions in Yeovil and the surrounding Somerset area.
- Guide price in YeovilFrom £21,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsBA20, BA21, BA22

Flat roof extension prices in Yeovil
Labour and material costs vary across the UK, so for Yeovil we use our South West England factor (×1.02). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Yeovil: £1,780 to £3,420 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £21,000 – £25,500 | £25,000 – £32,000 | £31,500 – £41,500 |
| 4 m × 5 m 20 m² | £35,500 – £42,000 | £41,500 – £53,500 | £53,000 – £68,500 |
| 5 m × 6 m 30 m² | £53,500 – £63,000 | £62,500 – £80,000 | £79,500 – £103,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
Is a flat roof extension right for your house?
- Extensions under first-floor windows where a pitch will not fit
- Modern and 1930s onwards houses
- Homeowners who want maximum light from above
Height is often what decides a flat roof. Under first-floor windows, a pitched roof may not fit at all; a flat roof keeps the extension low while still giving a good ceiling height inside.
Extensions in and around Yeovil
Across BA20, BA21, BA22, we can visit, measure and advise. Nearby, we also take on projects in Bridgwater (21 miles), Taunton (21 miles), Frome (24 miles), Burnham-on-Sea (26 miles).
In the South West, local stone, render and brick vary from town to town, so matching materials is a big part of designing an extension that looks right.
Planning and approvals in Yeovil
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions people ask about flat roof extensions
Do I need building regulations approval in Yeovil?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Yeovil?
Yes. We cover Yeovil and the surrounding parts of Somerset. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Yeovil, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,780 to £3,420 per m² including VAT.
Book a free site visit in Yeovil
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.