Two-storey wraparound extensions in Thornhill

Quick reference for homeowners in Thornhill.

Postcode districts: CF3 and CF23
County / area: Cardiff and the Vale of 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: Rhiwbina (1.3 miles), Whitchurch (Cardiff and the Vale of Glamorgan) (2.4 miles), Caerphilly (2.5 miles)
Distance to Cardiff: about 4.3 miles
First visit: Free, no obligation

About a two-storey wraparound extension

A two-storey wraparound extension is an L-shaped addition that extends both the side and the rear of your house, on two floors. It gives one of the largest gains in floor space of any extension, typically a big open-plan kitchen and living area below and two or more bedrooms or bathrooms above.

Thornhill sits about 4.3 miles from Cardiff. Closer to home, Rhiwbina is 1.3 miles away and Whitchurch (Cardiff and the Vale of Glamorgan) 2.4 miles.

What it costs in Thornhill

Using our Wales rates, a two-storey wraparound extension with an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space) comes to about £111,000–£152,000, 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	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 Thornhill

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 Thornhill homes

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.

The corner post

At the outside corner of the L, there is no existing wall to carry the floor above. Opening the ground floor fully usually means a steel frame or a corner post, and the engineer's design sets how slim it can be. We decide early whether you want a clear corner or a visible post.

How we'd run your project

Look at the house
We start in Thornhill with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.

Questions about two-storey wraparound extensions in Thornhill

How much does a two-storey wraparound extension cost in Thornhill?

Our guide for Wales, which covers Thornhill, is £1,980–£2,710 per m² including VAT. 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) comes to about £111,000–£152,000. 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 Thornhill?

We cover Thornhill (CF3 and CF23) and nearby places including Rhiwbina, Whitchurch (Cardiff and the Vale of Glamorgan) and Caerphilly, plus the rest of Cardiff and the Vale of Glamorgan. The first site visit is free.

Who handles building regulations for a project in Thornhill?

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 stay at home during a wraparound extension?

Many people do, but a wraparound affects two sides of the house and usually the kitchen, so there will be weeks without a full kitchen. We plan a temporary kitchen, keep a route through the house and seal off the work area. For some families, moving out while the rear wall is opened up is easier.

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.

Nearby

The same service in neighbouring towns:

Other extensions in Thornhill

All two-storey extension services in Thornhill · Two-storey wraparound extensions across Cardiff and the Vale of Glamorgan

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