St Leonards-on-Sea, East Sussex
Semi-detached rear extension in St Leonards-on-Sea
We plan and build rear extensions for semi-detached houses for homeowners in St Leonards-on-Sea. 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.
We cover St Leonards-on-Sea (TN34, TN37 and TN38) as part of our East Sussex work. Semi-detached houses are common across East Sussex, and their side access makes rear extensions quicker to build.
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 St Leonards-on-Sea?
In St Leonards-on-Sea, 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 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in St Leonards-on-Sea?
Whether your semi-detached rear extension in St Leonards-on-Sea needs a planning application depends on its size, your house and any local restrictions.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres 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 St Leonards-on-Sea like to extend?
Around St Leonards-on-Sea the housing ranges from inter-war semis to 1960s and 1970s estates with good-sized gardens. Many of the newer estates had permitted development rights removed by condition, so we check the planning history before anything is drawn.
How a semi-detached rear extension in St Leonards-on-Sea 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.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Semi-detached rear extensions near St Leonards-on-Sea
Neighbouring places we cover include Hastings (1.5 miles) and Bexhill-on-Sea (3.3 miles).
- Semi-detached rear extension in Hastings
- Semi-detached rear extension in Bexhill-on-Sea
- Semi-detached rear extension in Hailsham
- Semi-detached rear extension in Eastbourne
- Semi-detached rear extension in Seaford
Other work in St Leonards-on-Sea:
FAQ
Semi-detached rear extension questions in St Leonards-on-Sea
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 you handle building control in St Leonards-on-Sea?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
How long does a rear extension take to build in St Leonards-on-Sea?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
How much does a semi-detached rear extension cost in St Leonards-on-Sea?
As a guide, £2,130–£3,470 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £25,500–£41,500 at that rate. Your written price follows the survey.
Can you match the brick or stone on my St Leonards-on-Sea house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.