Single-storey rear extensions in Calne
Our design and build teams take on single-storey extensions in Calne, from the first measured survey through planning and building control to the finished room.
- Guide price in CalneFrom £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 districtsSN11
What is included
- Building regulations drawings and structural calculations
- Measured survey and design
- Planning route checked and the right approval obtained
- Doors, windows, insulation, plastering and first fix to finish
- Flat or pitched roof, rooflights or lantern
Extensions in and around Calne
We cover Calne and the postcode districts SN11. We also work in nearby Chippenham (6 miles), Devizes (7 miles), Melksham (8 miles), Trowbridge (12 miles).
For homes towards Somerset, Bath is around 16 miles away. South West homes range from terraced streets in the cities to stone cottages and bungalows in the countryside, and conservation areas are common in historic centres.
Will the council need to approve it?
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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).
Guide prices for Calne
These guide figures apply our South West England adjustment (×1.02) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Calne: £1,780 to £3,470 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 – £42,000 |
| 4 m × 5 m 20 m² | £35,500 – £42,000 | £41,500 – £53,500 | £53,000 – £69,500 |
| 5 m × 6 m 30 m² | £53,500 – £63,000 | £62,500 – £80,000 | £79,500 – £104,500 |
For a figure based on your own dimensions, use our guide-price tool.
How the project works
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
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Single-storey extension questions answered
Do you cover all of Calne?
Yes. We cover Calne and the surrounding parts of Wiltshire. Site visits are free and there is no obligation.
How long does a single-storey extension take to build in Calne?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Will my neighbours in Calne be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Can I stay in the house during the build?
Usually yes. Most of the work happens outside until the final weeks, when we open the rear wall. We plan that stage carefully and seal the opening with a temporary screen to keep dust down.
Will I need a steel beam?
Almost always. Opening up the rear wall to join the new room to the house needs a beam, usually steel, sized by a structural engineer. It is included in our quotes.
Book a free site visit in Calne
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.