Southampton house extensions
We design and build house extensions for homes in Southampton and the surrounding Hampshire area, with guide prices adjusted for the region.
- Postcode districtsSO14, SO15, SO16, SO17, SO18, SO19
- Price regionSouth East England (×1.12)
- Planning rulesEngland
- Site visitFree, no obligation
What works best for Southampton houses?
Homes across the South East range from Victorian terraces in the older town centres to large detached houses on the edges, so the right extension type varies street by street.
For many houses here, single-storey rear extensions, orangery extensions or double-storey extensions gives the most useful space for the budget.
Southampton and surrounding towns
Postcode districts we cover around Southampton include SO14, SO15, SO16, SO17, SO18, SO19. The same team covers Hythe (3 miles), Totton (4 miles), Eastleigh (5 miles), Fareham (10 miles), Winchester (12 miles), all within easy reach. For homes towards Isle of Wight, Cowes is around 11 miles away.
Do extensions in Southampton need planning permission?
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).
Guide prices for Southampton
Prices on this page use our South East England factor of ×1.12, 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) |
|---|---|---|
| Kitchen extensions | 20 m² | £47,000 – £59,500 |
| Wraparound extensions | 25 m² | £64,000 – £81,500 |
| Conservatory replacement extensions | 14 m² | £33,500 – £43,500 |
| Orangery extensions | 16 m² | £50,000 – £63,000 |
| Double-storey extensions | 32 m² | £64,500 – £84,500 |
| Single-storey rear extensions | 20 m² | £45,500 – £58,500 |
All extension types we build in Southampton
- Utility and boot room extensions · from £15,500
- Porch extensions · from £4,450
- Side extensions · from £24,500
- Annexe extensions · from £61,500
- Timber frame extensions · from £23,500
- Single-storey rear extensions · from £23,500
- Pitched roof extensions · from £24,500
- Kitchen extensions · from £30,000
- Glass box extensions · from £33,500
- Planning permission for extensions · from £350
- Extension plans and drawings · from £1,300
- Conservatory replacement extensions · from £22,000
- Wraparound extensions · from £40,000
- Flat roof extensions · from £23,500
- Double-storey extensions · from £42,500
- Home office extensions · from £17,500
- Orangery extensions · from £33,500
- Extensions over a garage · from £26,500
- Building regulations for extensions · from £1,000
- Side return extensions · from £20,000
- Bedroom extensions · from £29,000
- Bungalow extensions · from £29,000
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
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
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.
Questions about extensions in Southampton
How much does an extension cost in Southampton?
Using our South East England factor (×1.12), a standard-spec single-storey extension of 20 m² is a guide £45,500 to £58,500 including VAT, and a 32 m² two-storey extension £64,500 to £84,500. Your written price follows the survey.
Do I need planning permission for an extension in Southampton?
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.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Southampton, and the guide-price tool gives a range for your own size and finish in about a minute.
Book a free site visit in Southampton
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.