Extending your home in Portishead
From a small utility to a two-storey addition, we take on house extensions throughout Portishead, starting with a free visit and a planning check.
- Postcode districtsBS20
- Price regionSouth West England (×1.02)
- Planning rulesEngland
- Site visitFree, no obligation
What works best for Portishead houses?
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.
Start by comparing single-storey rear extensions, annexe extensions and orangery extensions: between them they cover most of the layouts we see requested for houses like these.
Approvals for an extension in Portishead
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).
What extensions cost in Portishead
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) |
|---|---|---|
| Side return extensions | 11 m² | £26,500 – £34,000 |
| Wraparound extensions | 25 m² | £58,500 – £74,000 |
| Extensions over a garage | 12 m² | £25,500 – £33,500 |
| 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 |
Areas we cover around Portishead
Across BS20, we can visit, measure and advise. Neighbouring towns we cover include Nailsea (3 miles), Clevedon (5 miles), Keynsham (13 miles), Weston-super-Mare (13 miles), Bath (19 miles). Just over the Gloucestershire border, Kingswood is about 11 miles away.
Choose an extension type
- Timber frame extensions · from £21,000
- Conservatory replacement extensions · from £20,000
- Bedroom extensions · from £26,500
- Kitchen extensions · from £27,500
- Side return extensions · from £18,000
- Extension plans and drawings · from £1,200
- Wraparound extensions · from £36,500
- Home office extensions · from £16,000
- Extensions over a garage · from £24,000
- Side extensions · from £22,000
- Porch extensions · from £4,050
- Flat roof extensions · from £21,000
- Bungalow extensions · from £26,500
- Orangery extensions · from £30,500
- Single-storey rear extensions · from £21,000
- Pitched roof extensions · from £22,500
- Planning permission for extensions · from £350
- Double-storey extensions · from £38,500
- Annexe extensions · from £56,000
- Building regulations for extensions · from £900
- Glass box extensions · from £30,500
- Utility and boot room extensions · from £14,000
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 draw the design, agree it with you and handle planning or permitted development checks and building regulations.
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 Portishead
How much does an extension cost in Portishead?
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 Portishead?
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.
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.
Do you cover all of Portishead?
Yes, including the surrounding parts of Somerset. Site visits are free and there is no obligation.
Book a free site visit in Portishead
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.