Carmarthen, West Wales
Single-storey rear extension in Carmarthen
Ground-floor space across the back of the house, usually for a kitchen, dining or family room. If you live in Carmarthen and want to know what a single-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Carmarthen and its postcode districts SA31 are part of our West Wales coverage. A single-storey rear extension in Carmarthen 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 Carmarthen?
For Carmarthen we work from the Wales rate: £1,770–£2,880 per square metre of new floor, including VAT, 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 Carmarthen?
Here is how the rules in Wales apply to a single-storey rear extension in Carmarthen.
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. At the first visit we measure what is there now and tell you which route fits: permitted development or a householder planning application.
What are homes in Carmarthen like to extend?
Older terraces near the centre and post-war semis further out are typical of Carmarthen. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start.
How a single-storey rear extension in Carmarthen 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.
Paperwork handled
Planning or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
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 Carmarthen
We also build single-storey rear extensions in nearby Llanelli (13.5 miles) and Ammanford (14.2 miles).
- Single-storey rear extension in Llanelli
- Single-storey rear extension in Ammanford
- Single-storey rear extension in Gorseinon
- Single-storey rear extension in Clydach
- Single-storey rear extension in Swansea
Other work in Carmarthen:
FAQ
Single-storey rear extension questions in Carmarthen
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.
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 I need a structural engineer?
Yes for the beam over the new opening and usually for the foundations. Their calculations go to building control with the drawings.
Can you match the brick or stone on my Carmarthen house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Do I need planning permission for a rear extension in Carmarthen?
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.
Is the site visit in Carmarthen free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.