Cardiff, Cardiff and the Vale
Single-storey rear extension in Cardiff
Single-storey rear extension in Cardiff: ground-floor space across the back of the house, usually for a kitchen, dining or family room. We measure the house, show you what the rules allow, price it in writing and build it.
Cardiff and its postcode districts CF3, CF5, CF11 and CF14 are part of our Cardiff and the Vale coverage. A single-storey rear extension in Cardiff is mostly built from the garden side, so the house stays usable for most of the job.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a single-storey rear extension cost in Cardiff?
In Cardiff, our guide for a single-storey 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 for a single-storey rear extension in Cardiff?
Here is how the rules in Wales apply to a single-storey rear extension in Cardiff.
In Wales a single-storey rear extension can often be permitted development if it projects no more than 4 metres beyond the rear wall and is no more than 4 metres high. Wales has no prior approval route for deeper extensions, so anything bigger needs a householder planning application.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Cardiff like to extend?
Older terraces near the centre and post-war semis further out are typical of Cardiff. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start.
How a single-storey rear extension in Cardiff comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Single-storey rear extensions near Cardiff
Close by, we work in Whitchurch, about 2.8 miles away, and Penarth, about 2.9 miles away.
- Single-storey rear extension in Whitchurch
- Single-storey rear extension in Penarth
- Single-storey rear extension in Rhiwbina
- Single-storey rear extension in Caerphilly
- Single-storey rear extension in Barry
Other work in Cardiff:
FAQ
Single-storey rear extension questions in Cardiff
What postcode areas do you cover around Cardiff?
Including CF3, CF5, CF11, CF14, CF23 and CF24, and the surrounding Cardiff and the Vale area.
Do I need planning permission for a rear extension in Cardiff?
Often not for a single-storey rear extension of up to 4 metres under Welsh permitted development. Wales has no prior approval route for deeper extensions.
Can I stay in the house during the build?
Usually yes. The noisiest, dustiest stage, removing the back wall, is kept to the final weeks and screened off. Most families set up a temporary kitchen elsewhere in the house.
Is the site visit in Cardiff free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Do you handle building control in Cardiff?
Yes. We apply to the council or a registered approver under the Welsh regulations and hand over the completion certificate.