Lancashire
Rear extensions for detached houses in Lancashire
Wider, deeper rear extensions with room for vaulted roofs and big glazing. Across Lancashire we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Preston, Burnley and Blackburn.
Detached houses in Lancashire often have room for a deeper rear extension under England's prior approval route or a full-width design. Lancashire has long runs of terraced houses with back yards and alleys, plus 1930s semis further out. Yard extensions on terraces are often single-storey and close to both boundaries.
How much does a detached house rear extension cost in Lancashire?
Guide prices for a detached house rear extension in Lancashire start from our North West England rate of £1,830–£3,010 per square metre, including VAT. North West prices sit below our West Midlands baseline; access on terraced streets is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 4 m wide × 6 m deep (24 m²) | £44,000–£72,000 |
| 5 m wide × 8 m deep (40 m²) | £73,500–£120,500 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission in Lancashire?
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.
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.
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.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent.
Where in Lancashire 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 Lancashire?
We cover 28 towns and districts in Lancashire, including Preston, Burnley and Blackburn.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.