Billingham, County Durham
Semi-detached rear extension in Billingham
Semi-detached rear extension in Billingham: single or two-storey extensions for semi-detached houses, with side access and one party wall. We measure the house, show you what the rules allow, price it in writing and build it.
Billingham sits in County Durham, with postcode districts including TS23. Semi-detached houses are common across County Durham, 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 Billingham?
Guide prices for a semi-detached rear extension in Billingham start from our North East England rate of £1,710–£2,790 per square metre, including VAT. North East prices are among the lowest in our range; former mining ground is the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £20,500–£33,500 |
| 4 m wide × 5 m deep (20 m²) | £34,000–£56,000 |
| 4 m wide × 6 m deep (24 m²) | £41,000–£67,000 |
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 Billingham?
Planning for a semi-detached rear extension in Billingham follows the English householder rules.
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.
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. 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 Billingham like to extend?
Brick terraces, colliery houses and post-war semis make up much of Billingham. Former mining areas often need a coal mining risk check before foundations are designed.
How a semi-detached rear extension in Billingham comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
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 Billingham
From Billingham, the nearest places we also cover are Stockton-on-Tees (1.8 miles) and Middlesbrough (2.4 miles).
- Semi-detached rear extension in Stockton-on-Tees
- Semi-detached rear extension in Middlesbrough
- Semi-detached rear extension in Thornaby-on-Tees
- Semi-detached rear extension in Ingleby Barwick
- Semi-detached rear extension in Yarm
Other work in Billingham:
FAQ
Semi-detached rear extension questions in Billingham
How long does a rear extension take to build in Billingham?
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 Billingham?
As a guide, £1,710–£2,790 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £20,500–£33,500 at that rate. Your written price follows the survey.
Do I need a party wall agreement?
Usually with the attached neighbour, in England and Wales.
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 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.
What postcode areas do you cover around Billingham?
Including TS23, and the surrounding County Durham area.