Cardiff and the Vale
Kitchen-diner rear extensions in Cardiff and the Vale
An open-plan kitchen, dining and family room that opens straight onto the garden. Across Cardiff and the Vale we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Cardiff, Barry and Penarth.

For Cardiff kitchens we plan the extraction route and the island drainage before the slab is poured, so nothing has to be chased in later. Older terraces near the centre and post-war semis further out are typical of Cardiff and the Vale. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start.
How much does a kitchen-diner rear extension cost in Cardiff and the Vale?
In Cardiff and the Vale, our guide for a kitchen-diner rear extension is £1,770–£2,880 per square metre including VAT for a standard specification. Prices in Wales sit below our West Midlands baseline; sloping sites are the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,000–£34,500 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£57,500 |
| 4 m wide × 6 m deep (24 m²) | £42,500–£69,000 |
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 Cardiff and the Vale?
The Welsh Government's householder rules let many homes add a single-storey rear extension up to 4 metres deep and 4 metres high without a planning application. Deeper projects go through a householder application, because Wales has no prior approval route.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent.
Where in Cardiff and the Vale do we work?
FAQ
Questions people ask
Should the sink face the garden?
If the plan allows, an island sink or hob facing the glass is a common choice. It needs a floor-level drain run, which is easy to lay in a new slab.
Can I have underfloor heating?
Yes. Wet underfloor heating in the new screed is the usual choice, often with the old room's radiators kept or replaced.
Where does the cooker extraction go?
Through the new wall or roof, ducted to outside. Recirculating hoods are possible but less effective.
Do you cover all of Cardiff and the Vale?
We cover 6 towns and districts in Cardiff and the Vale, including Cardiff, Barry and Penarth.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.