Double-storey extensions in Chiswick

Covering Chiswick

We work in Chiswick (W4) and the places around it, including Acton, Barnes and Shepherd's Bush.

Homes in London

Much of London’s housing is Victorian and Edwardian terraces, which is why side return extensions, rear dormers and mansards are so common. Many streets are in conservation areas, and several boroughs use Article 4 directions that remove some permitted development rights.

What do you get with a double-storey extension?

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.

Householder planning application
Structural engineer’s design and calculations
Joining the new first floor to the existing landing

What is the guide price for a double-storey extension in Chiswick?

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

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

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. Expect around eight weeks for a decision once the application is validated.

What should Chiswick 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.

From first call to completion

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.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

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.

Will we need to move out?

Most people stay. The noisiest stage is when we break through into the existing first floor, which we plan for a short window.

Who deals with the council for a project in Chiswick?

We do. We prepare the drawings, submit planning or permitted development paperwork if needed, and arrange building control inspections.

Also covering

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