Double-storey extensions in Caerphilly

Covering Caerphilly

We work in Caerphilly (CF83) and the places around it, including Whitchurch, Pontypridd and Cardiff.

Homes in Gwent

Welsh homes include long terraces built into hillsides, stone cottages and modern estates, and sloping sites often shape how and where an extension can go.

What do you get with a double-storey extension?

A double-storey extension adds new rooms on both the ground and first floor in one build, typically a larger kitchen or living space downstairs and an extra bedroom or bathroom above. Because the roof and foundations are shared, the cost per square metre is usually lower than a single-storey extension.

Structural engineer’s design and calculations
Foundations, steelwork, brick and block walls, roof
Windows, insulation, plastering, electrics and plumbing

How much does a double-storey extension cost in Caerphilly?

What double-storey extensions typically cost. These are guide ranges; the written quote for your house replaces them.

Double-storey extensions	Guide price incl. VAT
Standard specification	£2,400 to £2,900 per m²
Good specification	£2,900 to £3,400 per m²
High specification	£3,400 to £3,850 per m²

Do you need permission for a double-storey extension in Caerphilly?

Welsh projects need planning clearance from the council under Welsh rules, building regulations approval under the Welsh approved documents, and party wall notices where the work affects a neighbour’s wall or foundations.

Most two-storey extensions in Wales need householder planning permission from the council.

What can affect a double-storey extension?

Side extensions close to a boundary are often set back or stepped down so they do not create a terraced effect.
The new roof is tied into the old one, so roof tiles and ridge details need to match.

What happens after I enquire?

Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

Your questions answered

How much does a two-storey extension cost?

Typically about £2,400 to £3,850 per square metre of new floor area including VAT. A 40 m² extension across two floors is often around £100,000 to £150,000 depending on specification.

How long does a two-storey extension take?

Around 14 to 24 weeks on site, plus the planning period before that.

How do I get a price for double-storey extensions in Caerphilly?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Also covering

Learn more about double-storey extensions, or see every project we cover in Caerphilly.