Cumbria
Rear extensions for detached houses in Cumbria
Wider, deeper rear extensions with room for vaulted roofs and big glazing. We design and build rear extensions across Cumbria, from Carlisle and Barrow in Furness to Kendal, covering single-storey kitchen extensions, two-storey additions, side returns and wraparounds.
Detached houses in Cumbria often have room for a deeper rear extension under England's prior approval route or a full-width design. Cumbria 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 Cumbria?
In Cumbria, our guide for a detached house rear extension is £1,830–£3,010 per square metre including VAT for a standard specification. 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 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission in Cumbria?
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.
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 Cumbria 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 Cumbria?
We cover 7 towns and districts in Cumbria, including Carlisle, Barrow in Furness and Kendal.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.