Double-storey extensions in Carshalton

Covering Carshalton

Our coverage around Carshalton (SM5) also includes Sutton (2 miles to the south-west) and Mitcham.

Homes in London

London projects often mean working on period terraces with neighbours on both sides, tight access through the house and conservation area controls, so careful planning and party wall work matter as much as the build.

What does a double-storey extension involve?

Two-storey work has to sit comfortably with the house and the neighbours, so most of the design effort goes into the roofline, window positions and how the new first floor connects to the landing. We handle the planning application, the structural design and the building control process, then build, roof and finish both floors.

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 Carshalton?

Guide prices for double-storey extensions, including VAT where it applies. Your fixed price is confirmed in writing after the survey.

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

How is a double-storey extension approved in Carshalton?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

Two-storey rear extensions can sometimes be permitted development in England (no more than 3 m deep, at least 7 m from the rear boundary, roof pitch to match), but most two-storey and all two-storey side extensions need householder planning permission.

What should I think about before starting?

Neighbours’ light is assessed using the 45-degree guide many councils use.
The first-floor link can mean moving a bathroom or reshaping the landing.

What are the steps?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

Questions about a double-storey extension in Carshalton

Does a two-storey extension need planning permission?

Usually yes. In England some two-storey rear extensions are permitted development, but side extensions over one storey always need planning permission.

Is a two-storey extension better value than a single-storey one?

Per square metre, usually yes, because the foundations and roof serve two floors of space.

Do you work in Carshalton?

Yes. Carshalton is within our coverage for double-storey extensions, along with nearby Sutton and Mitcham.

Double-storey extensions near Carshalton

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