Extensions in Warminster: design, planning and build
Planning an extension in Warminster? Compare extension types, see guide prices adjusted for Warminster and book a free site visit.
- Postcode districtsBA12
- Price regionSouth West England (×1.02)
- Planning rulesEngland
- Site visitFree, no obligation
Planning rules in Warminster
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.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Areas we cover around Warminster
Across BA12, we can visit, measure and advise. We also work in nearby Trowbridge (10 miles), Melksham (14 miles), Devizes (14 miles), Salisbury (18 miles), Chippenham (20 miles). For homes towards Somerset, Frome is around 7 miles away.
Popular extension prices in Warminster
Prices on this page use our South West England factor of ×1.02, include VAT at 20% and cover the build; your written price follows a survey and agreed drawings.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Extensions over a garage | 12 m² | £25,500 – £33,500 |
| Conservatory replacement extensions | 14 m² | £30,500 – £39,500 |
| Side return extensions | 11 m² | £26,500 – £34,000 |
| Wraparound extensions | 25 m² | £58,500 – £74,000 |
| Kitchen extensions | 20 m² | £42,500 – £54,500 |
| Double-storey extensions | 32 m² | £58,500 – £77,000 |
Choosing the right extension in Warminster
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.
For many houses here, single-storey rear extensions, pitched roof extensions or annexe extensions gives the most useful space for the budget.
Every extension type in Warminster
- Side return extensions · from £18,000
- Extension plans and drawings · from £1,200
- Single-storey rear extensions · from £21,000
- Annexe extensions · from £56,000
- Kitchen extensions · from £27,500
- Home office extensions · from £16,000
- Orangery extensions · from £30,500
- Utility and boot room extensions · from £14,000
- Double-storey extensions · from £38,500
- Planning permission for extensions · from £350
- Pitched roof extensions · from £22,500
- Extensions over a garage · from £24,000
- Bungalow extensions · from £26,500
- Conservatory replacement extensions · from £20,000
- Wraparound extensions · from £36,500
- Building regulations for extensions · from £900
- Side extensions · from £22,000
- Porch extensions · from £4,050
- Flat roof extensions · from £21,000
- Timber frame extensions · from £21,000
- Bedroom extensions · from £26,500
- Glass box extensions · from £30,500
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions about extensions in Warminster
How much does an extension cost in Warminster?
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.
Do you cover all of Warminster?
Yes, including the surrounding parts of Wiltshire. Site visits are free and there is no obligation.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Do I need planning permission for an extension in Warminster?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
Book a free site visit in Warminster
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.