Single-storey rear extensions in Chiswick: design, approvals and build
A single-storey extension in Chiswick starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in ChiswickFrom £27,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsSW13, SW14, W3, W4, W6
Do I need planning permission in Chiswick?
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
The planning position for a specific Chiswick address depends on its history and any designations, which is why we check it at the first visit.
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).
Covering Chiswick
Site visits are available across Chiswick (SW13, SW14, W3, W4, W6, W12). We also work in nearby Acton (1 mile), Barnes (1 mile), Shepherds Bush (2 miles), Notting Hill (3 miles).
In London, space is at a premium and gardens are often short, so side returns, wraparounds and carefully planned rear extensions tend to make the most of every metre.
How much does a single-storey extension cost in Chiswick?
Prices below are for Chiswick, using the London factor of ×1.3. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Chiswick: £2,280 to £4,420 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £27,000 – £32,000 | £31,500 – £41,000 | £40,500 – £53,500 |
| 4 m × 5 m 20 m² | £45,500 – £53,500 | £53,000 – £68,000 | £67,500 – £88,500 |
| 5 m × 6 m 30 m² | £68,000 – £80,000 | £79,500 – £101,500 | £101,000 – £133,000 |
Try the guide-price tool to see a range for your own size and finish.
Is a single-storey extension right for your house?
- Homeowners who want open-plan living onto the garden
- Semi-detached and detached houses with a usable rear garden
- Terraced houses that want a deeper kitchen across the full width
What happens next
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
We visit your Chiswick home, measure up, talk through what you want and check the planning position.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Common questions in Chiswick
Do I need building regulations approval in Chiswick?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Chiswick?
Yes. We cover Chiswick and the surrounding parts of Greater London. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Chiswick, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Can I stay in the house during the build?
Usually yes. Most of the work happens outside until the final weeks, when we open the rear wall. We plan that stage carefully and seal the opening with a temporary screen to keep dust down.
How deep can a single-storey rear extension be without planning permission?
In England, up to 3 m beyond the original rear wall on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Through the larger home extension prior approval scheme those depths rise to 6 m and 8 m. Wales, Scotland and Northern Ireland use their own rules, which we check for your address.
Book a free site visit in Chiswick
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.