Home extensions in Carmarthen
Planning an extension in Carmarthen? Compare extension types, see guide prices adjusted for Carmarthen and book a free site visit.
- Postcode districtsSA31
- Price regionWales (×0.93)
- Planning rulesWales
- Site visitFree, no obligation
Which extension suits a Carmarthen home?
In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.
Start by comparing side return extensions, pitched roof extensions and bungalow extensions: between them they cover most of the layouts we see requested for houses like these.
Carmarthen extension prices at a glance
Every figure below is a guide for Carmarthen, adjusted for Wales build costs (×0.93) and including VAT. Design and council fees are shown separately on each page.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Side return extensions | 11 m² | £24,500 – £31,000 |
| Orangery extensions | 16 m² | £41,500 – £52,500 |
| Single-storey rear extensions | 20 m² | £38,000 – £48,500 |
| Double-storey extensions | 32 m² | £53,500 – £70,000 |
| Wraparound extensions | 25 m² | £53,000 – £67,500 |
| Kitchen extensions | 20 m² | £39,000 – £49,500 |
Covering Carmarthen and nearby
We cover Carmarthen and the postcode districts SA31. We also work in nearby Llanelli (13 miles), Ammanford (14 miles), Haverfordwest (29 miles), Pembroke Dock (29 miles), Aberystwyth (40 miles). For homes towards West Glamorgan, Gorseinon is around 17 miles away.
Do extensions in Carmarthen need planning permission?
In Wales a single-storey rear extension can usually project up to 4 m beyond the rear wall without a planning application, if it is no more than 4 m high, keeps eaves to 3 m and overall height to 4 m within 2 m of a boundary, and covers no more than half the land around the original house. Wales has no larger home extension prior approval scheme.
In Wales a single-storey side return can fall within permitted development if it stays within the 4 m height limit and the width rules for side extensions. Conservation areas and listed buildings need consent, and the Party Wall Act applies to work on or near a shared wall.
In a conservation area, national park, National Landscape or World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
Building regulations approval is separate from planning. Wales has its own building regulations and approved documents; the council or a registered building control approver checks the plans, inspects the work and issues a completion certificate.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
Choose an extension type
- Utility and boot room extensions · from £13,000
- Double-storey extensions · from £35,000
- Extension plans and drawings · from £1,100
- Pitched roof extensions · from £20,500
- Porch extensions · from £3,700
- Conservatory replacement extensions · from £18,500
- Side extensions · from £20,000
- Side return extensions · from £16,500
- Single-storey rear extensions · from £19,500
- Home office extensions · from £14,500
- Extensions over a garage · from £22,000
- Building regulations for extensions · from £800
- Orangery extensions · from £27,500
- Flat roof extensions · from £19,500
- Kitchen extensions · from £25,000
- Timber frame extensions · from £19,500
- Bedroom extensions · from £24,000
- Bungalow extensions · from £24,000
- Annexe extensions · from £51,000
- Glass box extensions · from £27,500
- Wraparound extensions · from £33,000
- Planning permission for extensions · from £300
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions about extensions in Carmarthen
How much does an extension cost in Carmarthen?
Using our Wales factor (×0.93), a standard-spec single-storey extension of 20 m² is a guide £38,000 to £48,500 including VAT, and a 32 m² two-storey extension £53,500 to £70,000. Your written price follows the survey.
How long does an extension take in Carmarthen?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do I need planning permission for an extension in Carmarthen?
Not always. It depends on the size, position and your property's history. In Wales many single-storey rear extensions up to 4 m are permitted development.
Do you cover all of Carmarthen?
Yes, including the surrounding parts of Dyfed. Site visits are free and there is no obligation.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Book a free site visit in Carmarthen
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.