Cheshire
Flat-roof rear extensions in Cheshire
Warm flat roofs with lanterns, parapets and long-life membranes. Across Cheshire we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Warrington, Chester and Crewe.
Flat roofs are the usual choice for rear extensions because they stay below first-floor windows and take a lantern neatly. Stone and brick terraces are common around Cheshire. Where houses back onto a ginnel or alley, deliveries can come in from the rear, which makes the build tidier.
How much does a flat-roof rear extension cost in Cheshire?
In Cheshire, our guide for a flat-roof rear extension is £1,790–£2,910 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 |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,500–£35,000 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£58,500 |
| 4 m wide × 6 m deep (24 m²) | £43,000–£70,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission in Cheshire?
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.
New fabric must meet Approved Document L (2021 edition incorporating 2023 amendments): walls 0.18, roof 0.15 and floor 0.18 W/m²K, windows 1.4 W/m²K or Band B. Under the simple route, new windows, doors and rooflights should not exceed 25% of the extension floor area plus any openings removed; more glass is possible with a whole-house calculation.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent.
Where in Cheshire do we work?
FAQ
Questions people ask
How long does a flat roof last?
A well-built single-ply or GRP warm roof typically lasts 25 years or more.
Is a flat roof really flat?
No; it is built to falls so water drains to outlets or gutters.
Can I walk on it?
Not as a balcony without planning permission and a guarding design; it can be accessed for maintenance.
Do you cover all of Cheshire?
We cover 21 towns and districts in Cheshire, including Warrington, Chester and Crewe.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.