Seaham, County Durham
Single-storey rear extension in Seaham
Single-storey rear extension in Seaham: ground-floor space across the back of the house, usually for a kitchen, dining or family room. We measure the house, show you what the rules allow, price it in writing and build it.
Seaham sits in County Durham, with postcode districts including SR7. A depth of 3 to 4 metres keeps many single-storey rear extensions in Seaham within permitted development, subject to the house's planning history.
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 single-storey rear extension cost in Seaham?
A single-storey rear extension in Seaham is priced at £1,710–£2,790 per square metre including VAT as a guide, before kitchen fit-out and fees. 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 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a single-storey rear extension in Seaham?
The planning route for a single-storey rear extension in Seaham is set by England's householder rules and your council.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
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 Seaham like to extend?
Terraces and semis are typical around Seaham. On terraces a single-storey rear extension across the back yard is usually the practical choice; semis often have room for more.
How a single-storey rear extension in Seaham 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.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Single-storey rear extensions near Seaham
From Seaham, the nearest places we also cover are Ryhope (2.4 miles) and Hetton-le-Hole (4.4 miles).
- Single-storey rear extension in Ryhope
- Single-storey rear extension in Hetton-le-Hole
- Single-storey rear extension in Houghton-le-Spring
- Single-storey rear extension in Sunderland
- Single-storey rear extension in Peterlee
Other work in Seaham:
FAQ
Single-storey rear extension questions in Seaham
Is the site visit in Seaham free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do I need planning permission for a rear extension in Seaham?
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.
Will the extension make the room behind it dark?
Not if it is designed well. Rooflights or a lantern over the old back room, and a wide opening into it, keep daylight reaching the middle of the house.
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.
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.
What postcode areas do you cover around Seaham?
Including SR7, and the surrounding County Durham area.