Isleworth, Greater London
Two-storey rear extension in Isleworth
A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. If you live in Isleworth and want to know what a two-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
We cover Isleworth (TW3, TW5 and TW7) as part of our Greater London work. In Isleworth, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a two-storey rear extension cost in Isleworth?
For Isleworth we work from the London rate: £2,340–£3,510 per square metre of new floor, including VAT, standard specification. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £70,000–£105,500 |
| 4 m × 6 m footprint, two floors (48 m²) | £112,500–£168,500 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a two-storey rear extension in Isleworth?
Here is how the rules in England apply to a two-storey rear extension in Isleworth.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Isleworth like to extend?
Isleworth is mostly 1930s semis, short terraces and post-war houses, so full-width single-storey and two-storey rear extensions are realistic on many plots. Some later estates had permitted development rights removed by condition, so we check the planning history first.
How a two-storey rear extension in Isleworth comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Two-storey rear extensions near Isleworth
Neighbouring places we cover include Osterley (0.6 miles) and Hounslow (0.9 miles).
- Two-storey rear extension in Osterley
- Two-storey rear extension in Hounslow
- Two-storey rear extension in Heston
- Two-storey rear extension in Brentford
- Two-storey rear extension in Richmond
Other work in Isleworth:
FAQ
Two-storey rear extension questions in Isleworth
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Do you handle building control in Isleworth?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Will we need to move out?
Rarely. The first-floor opening is made late in the job and sealed with temporary screens.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.
Is the site visit in Isleworth free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do I need planning permission for a rear extension in Isleworth?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.