Two-storey rear extensions in Carmarthen

Carmarthen: the key facts for this kind of project.

Postcode districts: SA31, SA32 and SA33
County / area: Dyfed, Wales
Price region: Wales
Guide price: £51,500–£69,500 (£1,840–£2,480 per m²)
Approval route: It may be permitted development if the ground floor goes no more than 4 m and the first floor no more than 3 m beyond the original rear wall, with the first floor 10.5 m from the rear boundary.
Nearest towns: Tumble (9.7 miles), Cross Hands (10.3 miles), Burry Port (12.1 miles)
Distance to Llanelli: about 13.5 miles
First visit: Free, no obligation

About a two-storey rear extension

A two-storey rear extension suits you if you need more room on both floors and have a reasonably deep garden. You get one team for the whole job: a measured survey, the design, a check on whether permitted development applies, planning drawings where they are needed, structural design, building regulations approval and the build itself, carried out by vetted teams working under S&K. Every project starts with a free site visit.

Carmarthen sits about 13.5 miles from Llanelli. Closer to home, Tumble is 9.7 miles away and Cross Hands 10.3 miles.

What it costs in Carmarthen

Expect a two-storey rear extension in Carmarthen to land somewhere around £51,500–£69,500 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Our Wales guide rate is £1,840–£2,480 per m², including VAT. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,690–£2,290 per m²	£47,500–£64,000
Standard	£1,840–£2,480 per m²	£51,500–£69,500
Premium	£2,210–£2,980 per m²	£62,000–£83,500

Planning and building regulations in Carmarthen

In Wales, a two-storey rear extension can be permitted development if the ground floor goes no more than 4 m and the first floor no more than 3 m beyond the original rear wall, with the first floor at least 10.5 m from the rear boundary. Nothing within 2 m of a boundary can be higher than 4 m. Conservation areas and other protected areas are excluded, and a householder application costs £585.

Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.

Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).

Design points for Carmarthen homes

Foundations and drains

Foundations for two storeys carry more load than a single storey and may need to go deeper near trees or on clay. Rear extensions often sit near drains, so we check sewer records early, as building over or near a public sewer may need the water company's agreement.

Opening up the ground floor

Knocking through the old rear wall means steel beams to carry the first floor and roof above. The structural engineer sets the beam sizes, padstones and any posts, and we plan them early so the open-plan layout you want is the one that gets built.

How we'd run your project

Understand the brief
At your home in Carmarthen we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Carmarthen.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Questions about two-storey rear extensions in Carmarthen

How long does a two-storey rear extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils normally decide householder applications within 8 weeks), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Do I need planning permission for a two-storey rear extension in Carmarthen?

Carmarthen is in Wales, so Wales planning rules apply. It may be permitted development if the ground floor goes no more than 4 m and the first floor no more than 3 m beyond the original rear wall, with the first floor 10.5 m from the rear boundary. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Which postcodes do you cover around Carmarthen?

We cover Carmarthen (SA31, SA32 and SA33) and nearby places including Tumble, Cross Hands and Burry Port, plus the rest of Dyfed. The first site visit is free.

How much does a two-storey rear extension cost in Carmarthen?

Our guide for Wales, which covers Carmarthen, is £1,840–£2,480 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £51,500–£69,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Will a two-storey rear extension block my neighbour's light?

It can if it is too deep or too close to the boundary, which is why councils look closely at its effect on neighbouring windows and gardens. We test the design against light and outlook early, keep the first floor shorter or set in where needed, and use a hipped roof to reduce bulk on the boundary side.

Nearby

We also cover places near Carmarthen, including:

Other extensions in Carmarthen

All two-storey extension services in Carmarthen · Two-storey rear extensions across Dyfed

Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Carmarthen.