Two-storey wraparound extensions in Mountain Ash

The basics for Mountain Ash at a glance.

Postcode districts: CF45
County / area: Mid Glamorgan, Wales
Price region: Wales
Guide price: £111,000–£152,000 (£1,980–£2,710 per m²)
Approval route: Usually needs planning permission, because the combined side and rear works rarely meet every permitted development test.
Nearest towns: Abercanaid (2.8 miles), Ferndale (3.3 miles), Treharris (3.4 miles)
Distance to Rhondda: about 3.4 miles
First visit: Free, no obligation

About a two-storey wraparound extension

A two-storey wraparound extension suits a house with space both beside it and behind it, where you want to transform the layout rather than add a single room. You get one design for the whole L-shape, the planning application, structural design for the corner and the openings into the house, building regulations approval and the build, managed by us and carried out by vetted teams working under S&K.

Around Mountain Ash we also work in Abercanaid, Ferndale and Treharris, and across the rest of Mid Glamorgan. Postcode district in and near Mountain Ash: CF45.

What it costs in Mountain Ash

Guide prices for two-storey wraparound extensions in Wales are around £1,980–£2,710 per m² of new floor space, including VAT. For a typical project with an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space), that's roughly £111,000–£152,000. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.

Spec	Per m²	An L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space)
Essential	£1,820–£2,500 per m²	£102,000–£140,000
Standard	£1,980–£2,710 per m²	£111,000–£152,000
Premium	£2,370–£3,260 per m²	£133,000–£182,500

Planning and building regulations in Mountain Ash

In Wales, a wraparound would have to pass both the side and rear tests to be permitted development: 10.5 m to the opposite side boundary, a 1 m set-back from the front and no more than 50% added width, plus the 4 m and 3 m rear depth limits and 10.5 m to the rear boundary. Many wraparounds therefore need a householder application, which 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 Mountain Ash homes

Two roofs that meet

A wraparound needs the side roof and rear roof to join cleanly, often with a valley or hip where they meet. Getting pitches and ridge heights right keeps rainwater moving and avoids a bulky mass at the back corner, which neighbours and planners notice.

Daylight to the middle

A deep L-shaped plan can leave the middle of the ground floor dark, because the old rear rooms are now enclosed. We use wide rear openings, a well-placed stair and, where part of the extension is single storey, roof lights, while keeping total glazing within the Part L allowance.

How we'd run your project

Measure and listen
A visit to Mountain Ash to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
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.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Questions about two-storey wraparound extensions in Mountain Ash

Do I need planning permission for a two-storey wraparound extension in Mountain Ash?

Mountain Ash is in Wales, so Wales planning rules apply. Usually needs planning permission, because the combined side and rear works rarely meet every permitted development test. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Which postcodes do you cover around Mountain Ash?

We cover Mountain Ash (CF45) and nearby places including Abercanaid, Ferndale and Treharris, plus the rest of Mid Glamorgan. The first site visit is free.

How long does a two-storey wraparound 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.

Can a wraparound extension be part single, part two-storey?

Yes. Many wraparounds keep the rear part single storey with roof lights over the kitchen and put the two-storey part to the side. This can reduce the effect on neighbours and the cost. We set out both options at the design stage, so you can compare floor space against price before choosing.

Is a wraparound extension better than separate side and rear extensions?

Building both at once usually costs less than two separate projects, because you pay for one set-up, one scaffold, one roof junction and one set of approvals. It also lets the layout be designed as a whole. The trade-off is a larger single outlay and a longer build, often 16 to 24 weeks at this size.

Nearby

Other towns near Mountain Ash:

Other extensions in Mountain Ash

All two-storey extension services in Mountain Ash · Two-storey wraparound extensions across Mid Glamorgan

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