Two-storey side extensions in Merthyr Tydfil

Before you start in Merthyr Tydfil, here's what applies.

Postcode districts: CF47 and CF48
County / area: Mid Glamorgan, Wales
Price region: Wales
Guide price: £79,000–£106,500 (£1,890–£2,530 per m²)
Approval route: Can be permitted development in Wales if it is 10.5 m from the side boundary, set back 1 m from the front and doesn't widen the house by more than half; otherwise planning permission.
Nearest towns: Abercanaid (1.8 miles), Aberdare (3.8 miles), Rhymney (4 miles)
Distance to Rhondda: about 6.9 miles
First visit: Free, no obligation

About a two-storey side extension

A two-storey side extension suits a detached or semi-detached house with a side garden, driveway or garage wide enough to build on. You get a design that sits comfortably on the street, a planning application or permitted development check depending on your nation, structural design, building regulations approval and the build itself. We manage the whole process, and the work is carried out by vetted teams working under S&K.

We cover Merthyr Tydfil (CF47 and CF48) and the places around it, including Abercanaid (1.8 miles), Aberdare (3.8 miles) and Rhymney.

What it costs in Merthyr Tydfil

Using our Wales rates, a two-storey side extension with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £79,000–£106,500, including VAT. Bigger or more glazed designs cost more per m². Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,740–£2,330 per m²	£73,000–£98,000
Standard	£1,890–£2,530 per m²	£79,000–£106,500
Premium	£2,260–£3,040 per m²	£95,000–£127,500

Planning and building regulations in Merthyr Tydfil

In Wales, a two-storey side extension can be permitted development if it is at least 10.5 m from the boundary opposite the side wall, set back at least 1 m from the front of the house and does not increase the house's widest width by more than 50%. If it fails any test, or the house is in a protected area, 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 Merthyr Tydfil homes

Avoiding a terracing effect

Where semi-detached houses sit close together, side extensions on neighbouring houses can join up and turn a row of pairs into a terrace. Many councils ask for a gap to the boundary at first floor to stop this, so we check local guidance before fixing the width.

Access and services

Side extensions often cover the only route to the back garden, a gas meter, soil pipes or a drain run. We plan bin and bike access, move meters and pipes where needed and check drains early, because these items affect both cost and layout.

How we'd run your project

Measure and listen
A visit to Merthyr Tydfil to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Get it approved
Once you're happy with the design we submit it to the council for Merthyr Tydfil and deal with any questions from the planning officer.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Questions about two-storey side extensions in Merthyr Tydfil

How much does a two-storey side extension cost in Merthyr Tydfil?

Our guide for Wales, which covers Merthyr Tydfil, is £1,890–£2,530 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £79,000–£106,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Which postcodes do you cover around Merthyr Tydfil?

We cover Merthyr Tydfil (CF47 and CF48) and nearby places including Abercanaid, Aberdare and Rhymney, plus the rest of Mid Glamorgan. The first site visit is free.

Do I need planning permission for a two-storey side extension in Merthyr Tydfil?

Merthyr Tydfil is in Wales, so Wales planning rules apply. Can be permitted development in Wales if it is 10.5 m from the side boundary, set back 1 m from the front and doesn't widen the house by more than half; otherwise planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Who handles building regulations for a project in Merthyr Tydfil?

We handle it as part of the project. What's needed in Wales: building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency). We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

Can I build a two-storey side extension over my driveway?

Yes, if the drive is wide enough for a useful room and the council accepts the design. You may lose off-road parking, which some councils weigh up, and the foundations need to suit the ground below. We check parking, drains and meter positions at the free site visit before any drawings are prepared.

Nearby

Close to Merthyr Tydfil? We work across the area, including:

Other extensions in Merthyr Tydfil

All two-storey extension services in Merthyr Tydfil · Two-storey side extensions across Mid Glamorgan

Tell us about your house in Merthyr Tydfil and we'll call you back to arrange a free, no-obligation visit.