Sinfin, Derbyshire
Semi-detached rear extension in Sinfin
Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design, get the approvals for and build rear extensions for semi-detached houses in Sinfin and the surrounding area, with one contract from the first survey to building control sign-off.
Sinfin sits in Derbyshire, with postcode districts including DE1, DE23 and DE24. Semi-detached houses are common across Derbyshire, 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 Sinfin?
For Sinfin we work from the East Midlands rate: £1,840–£3,010 per square metre of new floor, including VAT, standard specification. 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 |
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 Sinfin?
The planning route for a semi-detached rear extension in Sinfin 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.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
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. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Sinfin like to extend?
Red-brick terraces and semis are typical of Sinfin. Coal-mining legacy areas in parts of the East Midlands can need a Coal Authority check before foundations are designed. Where a Sinfin semi already has a small lean-to at the back, we usually replace it rather than extend it.
How a semi-detached rear extension in Sinfin 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.
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 Sinfin
Neighbouring places we cover include Derby (2.9 miles) and Chaddesden (4.0 miles).
- Semi-detached rear extension in Derby
- Semi-detached rear extension in Chaddesden
- Semi-detached rear extension in Oakwood
- Semi-detached rear extension in Swadlincote
- Semi-detached rear extension in Burton upon Trent
Other work in Sinfin:
FAQ
Semi-detached rear extension questions in Sinfin
Is the site visit in Sinfin free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How much does a semi-detached rear extension cost in Sinfin?
As a guide, £1,840–£3,010 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £22,000–£36,000 at that rate. Your written price follows the survey.
What if my neighbour has already extended?
That can make a matching depth easier to justify. We measure theirs at the survey.
What postcode areas do you cover around Sinfin?
Including DE1, DE23 and DE24, and the surrounding Derbyshire area.
How long does a rear extension take to build in Sinfin?
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 Sinfin?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.