Annexe extensions in Acton: design, approvals and build
If you live in Acton and want more space without moving, an annexe extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in ActonFrom £71,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsTW8, W3, W4, W5, W12
Guide prices for Acton
For Acton we adjust our national guide rates by ×1.3, the factor we use for London. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Acton: £2,600 to £4,940 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £71,500 – £89,500 | £78,000 – £97,500 | £97,500 – £123,500 |
| One-bedroom annexe 35 m² | £91,000 – £114,000 | £109,000 – £136,500 | £136,500 – £173,000 |
| Larger annexe 45 m² | £117,000 – £146,500 | £140,000 – £175,500 | £175,500 – £222,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Who an annexe extension suits
- Multi-generational families
- Homes with a large side or rear garden
- Relatives who need support close by
Extensions in and around Acton
Our survey diary covers Acton, including TW8, W3, W4, W5, W12, W13. Nearby, we also take on projects in Chiswick (1 mile), Harlesden (2 miles), Shepherds Bush (2 miles), Willesden (2 miles).
East Molesey, in Surrey, is roughly 8 miles from Acton and also on our list. Across London, terraced houses with narrow side returns and tight access are the norm, which shapes everything from party wall notices to how materials reach the back garden.
Planning rules that apply in Acton
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Annexe extension questions answered
Will my neighbours in Acton be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
How long does an annexe extension take to build in Acton?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
Do you cover all of Acton?
Yes. We cover Acton and the surrounding parts of Greater London. Site visits are free and there is no obligation.
How much does an annexe extension cost?
Our guide range is about £2,600 to £4,940 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £109,000 to £136,500 at standard spec in Acton.
Does an annexe extension need planning permission?
Usually yes, because of its size and the way it will be used. Councils check that it stays ancillary to the main house, so the application must describe the use clearly.
Book a free site visit in Acton
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.