Extending your home in Trowbridge
Looking to extend your home in Trowbridge? Start here: extension types, guide prices for Trowbridge, the planning rules that apply and how a project runs.
- Postcode districtsBA14
- Price regionSouth West England (×1.02)
- Planning rulesEngland
- Site visitFree, no obligation
Covering Trowbridge and nearby
Our survey diary covers Trowbridge, including BA14. Nearby, we also take on projects in Melksham (5 miles), Devizes (10 miles), Warminster (10 miles), Chippenham (10 miles), Calne (12 miles). Just over the Somerset border, Bath is about 8 miles away.
Choosing the right extension in Trowbridge
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.
Depending on the plot, annexe extensions and orangery extensions are often the strongest options, with pitched roof extensions worth considering where there is room.
Guide prices for Trowbridge
We publish guide prices so you can budget before anyone visits. For Trowbridge they are adjusted by ×1.02, the factor we use across South West England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Conservatory replacement extensions | 14 m² | £30,500 – £39,500 |
| Side return extensions | 11 m² | £26,500 – £34,000 |
| Kitchen extensions | 20 m² | £42,500 – £54,500 |
| Single-storey rear extensions | 20 m² | £41,500 – £53,500 |
| Extensions over a garage | 12 m² | £25,500 – £33,500 |
Planning and building control in Trowbridge
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 England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
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).
Every extension type in Trowbridge
- Planning permission for extensions · from £350
- Porch extensions · from £4,050
- Home office extensions · from £16,000
- Double-storey extensions · from £38,500
- Conservatory replacement extensions · from £20,000
- Timber frame extensions · from £21,000
- Pitched roof extensions · from £22,500
- Utility and boot room extensions · from £14,000
- Orangery extensions · from £30,500
- Single-storey rear extensions · from £21,000
- Extension plans and drawings · from £1,200
- Flat roof extensions · from £21,000
- Kitchen extensions · from £27,500
- Side extensions · from £22,000
- Bungalow extensions · from £26,500
- Glass box extensions · from £30,500
- Extensions over a garage · from £24,000
- Building regulations for extensions · from £900
- Wraparound extensions · from £36,500
- Bedroom extensions · from £26,500
- Side return extensions · from £18,000
- Annexe extensions · from £56,000
Free site visit
We visit your Trowbridge home, measure up, talk through what you want and check the planning position.
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
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Trowbridge
How much does an extension cost in Trowbridge?
Using our South West England factor (×1.02), a standard-spec single-storey extension of 20 m² is a guide £41,500 to £53,500 including VAT, and a 32 m² two-storey extension £58,500 to £77,000. Your written price follows the survey.
How long does an extension take in Trowbridge?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do you cover all of Trowbridge?
Yes, including the surrounding parts of Wiltshire. Site visits are free and there is no obligation.
Who do I contract with?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Will my neighbours need to be told?
If you apply for planning or prior approval the council notifies them, and in England party wall notices may be needed for work near a shared boundary.
Book a free site visit in Trowbridge
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.