Wellingborough, Northamptonshire
Semi-detached rear extension in Wellingborough
Single or two-storey extensions for semi-detached houses, with side access and one party wall. If you live in Wellingborough and want to know what a semi-detached rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Wellingborough sits in Northamptonshire, with postcode districts including NN8. Where a Wellingborough semi already has a small lean-to at the back, we usually replace it rather than extend it.
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 Wellingborough?
A semi-detached rear extension in Wellingborough is priced at £1,840–£3,010 per square metre including VAT as a guide, before kitchen fit-out and fees. East Midlands prices sit a little below our West Midlands baseline.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £22,000–£36,000 |
| 4 m wide × 5 m deep (20 m²) | £37,000–£60,000 |
| 4 m wide × 6 m deep (24 m²) | £44,000–£72,000 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a semi-detached rear extension in Wellingborough?
The planning route for a semi-detached rear extension in Wellingborough is set by England's householder rules and your council.
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.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
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 Wellingborough like to extend?
Red-brick terraces and semis are typical of Wellingborough. Coal-mining legacy areas in parts of the East Midlands can need a Coal Authority check before foundations are designed.
How a semi-detached rear extension in Wellingborough 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.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
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 Wellingborough
Close by, we work in Rushden, about 4.0 miles away, and Kettering, about 6.7 miles away.
- Semi-detached rear extension in Rushden
- Semi-detached rear extension in Kettering
- Semi-detached rear extension in Northampton
- Semi-detached rear extension in Desborough
- Semi-detached rear extension in Corby
Other work in Wellingborough:
FAQ
Semi-detached rear extension questions in Wellingborough
Can you match the brick or stone on my Wellingborough house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
Is the site visit in Wellingborough free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How long does a rear extension take to build in Wellingborough?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Do you handle building control in Wellingborough?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.