Double-storey extensions in Chelsea

Covering Chelsea

Alongside Chelsea, we also cover Battersea, Fulham (1 miles to the west) and Notting Hill.

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.

Measured survey, design and planning drawings
Structural engineer’s design and calculations
Joining the new first floor to the existing landing

How much should I budget for a double-storey extension?

Indicative costs for double-storey extensions. London and the South East usually sit towards the top of each range.

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

Planning and building rules in Chelsea

English projects need planning clearance from the local council, building regulations sign-off from building control, and party wall notices where the work is on or near a shared boundary. We prepare and manage all three.

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 Chelsea homeowners check first?

Side extensions close to a boundary are often set back or stepped down so they do not create a terraced effect.
The first-floor link can mean moving a bathroom or reshaping the landing.

What are the steps?

Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
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 Chelsea

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.

How long does a two-storey extension take?

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

Can you visit a house in Chelsea to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Double-storey extensions near Chelsea

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