Part single, part two-storey extensions in Rhondda

Rhondda: the key facts for this kind of project.

Postcode districts: CF43
County / area: Mid Glamorgan, Wales
Price region: Wales
Guide price: £66,000–£91,000 (£1,840–£2,530 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: Ferndale (0.1 miles), Pentre (1.8 miles), Treorchy (2.4 miles)
First visit: Free, no obligation

About a part single, part two-storey extension

A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.

We cover Rhondda (CF43) and the places around it, including Ferndale (0.1 miles), Pentre (1.8 miles) and Treorchy.

What it costs in Rhondda

For budgeting in Rhondda, allow around £66,000–£91,000 for a part single, part two-storey extension with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). That's based on £1,840–£2,530 per m² including VAT for Wales. Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£1,690–£2,330 per m²	£61,000–£84,000
Standard	£1,840–£2,530 per m²	£66,000–£91,000
Premium	£2,210–£3,040 per m²	£79,500–£109,500

Planning and building regulations in Rhondda

In Wales, a part two-storey rear extension can be permitted development if the first floor goes no more than 3 m and the ground floor no more than 4 m beyond the original rear wall, with the first floor at least 10.5 m from the rear boundary. Conservation areas and other protected areas are excluded. If the design falls outside these limits, 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 Rhondda homes

The roof junction

Where the single-storey roof meets the two-storey wall you need a sound weathering detail, usually a lead or similar flashing, and enough height for roof lights or a lantern. We set the roof falls and the upstairs window sill heights together so they do not clash.

Where to put the two-storey part

The two-storey section usually works best away from the closest neighbour, with the single-storey part on that boundary side. We test a few positions against neighbours' windows, the upstairs layout and the roof shape before choosing the one to take forward.

How we'd run your project

Visit and first ideas
One of our team visits your house in Rhondda, checks the walls, roof and drains, and sketches out options with you.
Design and approvals
We draw the extension and check it against the rules for Wales, then apply for planning permission or a certificate of lawfulness, whichever fits.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Questions about part single, part two-storey extensions in Rhondda

How long does a part single, part two-storey 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.

Which postcodes do you cover around Rhondda?

We cover Rhondda (CF43) and nearby places including Ferndale, Pentre and Treorchy, plus the rest of Mid Glamorgan. The first site visit is free.

Do I need planning permission for a part single, part two-storey extension in Rhondda?

Rhondda 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.

Can the single-storey part be deeper than the two-storey part?

With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.

Which side should the two-storey part go on?

Usually the side furthest from the nearest neighbour's windows, so the single-storey part sits nearest them and keeps their light. Other factors are where the stairs land upstairs, which room needs the extra space and where drains run. We sketch options at the design stage and explain which is most likely to be approved.

Nearby

Other towns near Rhondda:

Other extensions in Rhondda

All two-storey extension services in Rhondda · Part single, part two-storey extensions across Mid Glamorgan

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.