Eastbourne, East Sussex
Semi-detached rear extension in Eastbourne
We plan and build rear extensions for semi-detached houses for homeowners in Eastbourne. Single or two-storey extensions for semi-detached houses, with side access and one party wall. Start with a free site visit, then a written price once the design is agreed.
Eastbourne and its postcode districts BN20, BN21 and BN23 are part of our East Sussex coverage. In Eastbourne we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Eastbourne?
In Eastbourne, our guide for a semi-detached rear extension is £2,130–£3,470 per square metre including VAT for a standard specification. South East prices run above our West Midlands baseline, mainly on labour rates and clay-soil foundations.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £25,500–£41,500 |
| 4 m wide × 5 m deep (20 m²) | £42,500–£69,500 |
| 4 m wide × 6 m deep (24 m²) | £51,000–£83,500 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a semi-detached rear extension in Eastbourne?
The planning route for a semi-detached rear extension in Eastbourne is set by England's householder rules and your council.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Eastbourne like to extend?
Commuter semis and detached houses make up much of Eastbourne, and longer gardens make England's prior approval route for deeper rear extensions worth considering.
How a semi-detached rear extension in Eastbourne comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Eastbourne
Neighbouring places we cover include Hailsham (6.6 miles) and Seaford (7.9 miles).
- Semi-detached rear extension in Hailsham
- Semi-detached rear extension in Seaford
- Semi-detached rear extension in Bexhill-on-Sea
- Semi-detached rear extension in Newhaven
- Semi-detached rear extension in Peacehaven
Other work in Eastbourne:
FAQ
Semi-detached rear extension questions in Eastbourne
Do I need planning permission for a rear extension in Eastbourne?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Is the site visit in Eastbourne free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How long does a semi extension take?
10 to 16 weeks on site for a single-storey extension.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
Can you match the brick or stone on my Eastbourne house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.