Isleworth home office extensions, designed and built
Planning a home office extension in Isleworth? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in IsleworthFrom £20,500 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time8–12 weeks on site
- Postcode districtsTW1, TW3, TW4, TW5, TW7
Is a home office extension right for your house?
- People who work from home most of the week
- Homes where a loft or garden room is not practical
- Households that need a second quiet room
Planning rules that apply in Isleworth
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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).
Working in Isleworth
Our survey diary covers Isleworth, including TW1, TW3, TW4, TW5, TW7, TW8. Nearby, we also take on projects in Hounslow (1 mile), Heston (2 miles), Richmond (2 miles), Southall (3 miles).
For homes towards Surrey, East Molesey is around 5 miles away. 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.
Home office extension prices in Isleworth
Labour and material costs vary across the UK, so for Isleworth we use our London factor (×1.3). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Isleworth: £2,400 to £4,420 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 3.2 m 8 m² | £20,500 – £25,000 | £22,000 – £28,500 | £28,000 – £35,500 |
| 3 m × 3.6 m 11 m² | £26,000 – £31,500 | £30,500 – £39,000 | £38,500 – £49,000 |
| 3 m × 5 m 15 m² | £36,000 – £43,000 | £41,500 – £53,000 | £52,500 – £66,500 |
For a figure based on your own dimensions, use our guide-price tool.
Our process, step by step
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 Isleworth home, measure up, talk through what you want and check the planning position.
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
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about a home office extension in Isleworth
Do you cover all of Isleworth?
Yes. We cover Isleworth and the surrounding parts of Greater London. Site visits are free and there is no obligation.
How long does a home office extension take to build in Isleworth?
On site, typically 8 to 12 weeks once approvals are in place. Before that, allow 4–10 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Isleworth, 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 claim the cost against tax?
Building work on your home is not normally an allowable business expense, and claiming it can have capital gains tax effects. Speak to an accountant before assuming any tax relief.
How much does a home office extension cost?
Our guide range is about £2,400 to £4,420 per m² including VAT. An 11 m² standard-spec office is typically £30,500 to £39,000 in Isleworth.
Book a free site visit in Isleworth
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.