Northumberland
Rear extensions for detached houses in Northumberland
Wider, deeper rear extensions with room for vaulted roofs and big glazing. Across Northumberland we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Blyth, Cramlington and Ashington.
Detached houses in Northumberland often have room for a deeper rear extension under England's prior approval route or a full-width design. Terraces and semis are typical around Northumberland. On terraces a single-storey rear extension across the back yard is usually the practical choice; semis often have room for more.
How much does a detached house rear extension cost in Northumberland?
For Northumberland we work from the North East England rate: £1,760–£2,880 per square metre of new floor, including VAT, standard specification. North East prices are among the lowest in our range; former mining ground is the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 4 m wide × 6 m deep (24 m²) | £42,000–£69,000 |
| 5 m wide × 8 m deep (40 m²) | £70,000–£115,000 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission in Northumberland?
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.
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.
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.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent.
Where in Northumberland do we work?
FAQ
Questions people ask
How deep can I extend a detached house?
4 metres under permitted development in England, or 8 metres with prior approval, outside designated land.
Can I have a vaulted ceiling?
Yes, with a pitched roof and exposed or boxed rafters, subject to the height limits.
Is an oak frame worth it?
It is a premium finish with a long life; it costs more than blockwork with a plain roof.
Do you cover all of Northumberland?
We cover 10 towns and districts in Northumberland, including Blyth, Cramlington and Ashington.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.