Home extensions in Dorset
From a small utility to a two-storey addition, we take on house extensions throughout Dorset, starting with a free visit and a planning check.
- Towns listed9
- Price regionSouth West England (×1.02)
- Planning rulesEngland
- Postcode districts37
Towns we cover in Dorset
Towns we cover here include Bournemouth, Poole, Weymouth, Christchurch.
Popular extension prices in Dorset
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) |
|---|---|---|
| Conservatory replacement extensions | 14 m² | £30,500 – £39,500 |
| Extensions over a garage | 12 m² | £25,500 – £33,500 |
| Wraparound extensions | 25 m² | £58,500 – £74,000 |
| Double-storey extensions | 32 m² | £58,500 – £77,000 |
| Orangery extensions | 16 m² | £45,500 – £57,500 |
| Single-storey rear extensions | 20 m² | £41,500 – £53,500 |
| Kitchen extensions | 20 m² | £42,500 – £54,500 |
Planning and building control in Dorset
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.
What works best for Dorset houses?
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.
Start by comparing single-storey rear extensions, orangery extensions and pitched roof extensions: between them they cover most of the layouts we see requested for houses like these.
Choose an extension type
- Glass box extensions · from £30,500
- Extensions over a garage · from £24,000
- Planning permission for extensions · from £350
- Home office extensions · from £16,000
- Wraparound extensions · from £36,500
- Kitchen extensions · from £27,500
- Porch extensions · from £4,050
- Double-storey extensions · from £38,500
- Conservatory replacement extensions · from £20,000
- Flat roof extensions · from £21,000
- Bungalow extensions · from £26,500
- Timber frame extensions · from £21,000
- Extension plans and drawings · from £1,200
- Single-storey rear extensions · from £21,000
- Utility and boot room extensions · from £14,000
- Bedroom extensions · from £26,500
- Building regulations for extensions · from £900
- Pitched roof extensions · from £22,500
- Annexe extensions · from £56,000
- Side extensions · from £22,000
- Orangery extensions · from £30,500
- Side return extensions · from £18,000
Neighbouring areas
Questions about extensions in Dorset
How much does an extension cost in Dorset?
With our South West England factor (×1.02), a standard-spec 20 m² single-storey extension is a guide £41,500 to £53,500 including VAT. Prices for every type are linked on this page.
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.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
How long does an extension take in Dorset?
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.
Book a free site visit in Dorset
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.