Hounslow house extensions
Looking to extend your home in Hounslow? Start here: extension types, guide prices for Hounslow, the planning rules that apply and how a project runs.
- Postcode districtsTW1, TW2, TW3, TW4, TW5, TW7
- Price regionLondon (×1.3)
- Planning rulesEngland
- Site visitFree, no obligation
Guide prices for Hounslow
Prices on this page use our London factor of ×1.3, include VAT at 20% and cover the build; your written price follows a survey and agreed drawings.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Extensions over a garage | 12 m² | £32,500 – £42,500 |
| Wraparound extensions | 25 m² | £74,500 – £94,500 |
| Double-storey extensions | 32 m² | £74,500 – £98,000 |
| Conservatory replacement extensions | 14 m² | £39,000 – £50,500 |
| Kitchen extensions | 20 m² | £54,500 – £69,000 |
| Side return extensions | 11 m² | £34,000 – £43,000 |
Covering Hounslow and nearby
Postcode districts we cover around Hounslow include TW1, TW2, TW3, TW4, TW5, TW7. We also work in nearby Isleworth (1 mile), Heston (1 mile), Richmond (2 miles), Hanworth (3 miles), Feltham (3 miles). West Molesey, in Surrey, is roughly 5 miles from Hounslow and also on our list.
Approvals for an extension in Hounslow
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 England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
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 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.
Applications are decided by the local planning authority (your district, borough or unitary council).
What works best for Hounslow houses?
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.
Start by comparing wraparound extensions, kitchen extensions and glass box extensions: between them they cover most of the layouts we see requested for houses like these.
All extension types we build in Hounslow
- Conservatory replacement extensions · from £26,000
- Flat roof extensions · from £27,000
- Planning permission for extensions · from £450
- Timber frame extensions · from £27,000
- Glass box extensions · from £39,000
- Single-storey rear extensions · from £27,000
- Bungalow extensions · from £34,000
- Bedroom extensions · from £33,500
- Double-storey extensions · from £49,000
- Side return extensions · from £23,000
- Side extensions · from £28,500
- Pitched roof extensions · from £28,500
- Kitchen extensions · from £35,000
- Porch extensions · from £5,200
- Annexe extensions · from £71,500
- Wraparound extensions · from £46,500
- Extension plans and drawings · from £1,550
- Building regulations for extensions · from £1,150
- Extensions over a garage · from £31,000
- Utility and boot room extensions · from £18,000
- Orangery extensions · from £39,000
- Home office extensions · from £20,500
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions about extensions in Hounslow
How much does an extension cost in Hounslow?
Using our London factor (×1.3), a standard-spec single-storey extension of 20 m² is a guide £53,000 to £68,000 including VAT, and a 32 m² two-storey extension £74,500 to £98,000. Your written price follows the survey.
Do you cover all of Hounslow?
Yes, including the surrounding parts of Greater London. Site visits are free and there is no obligation.
How long does an extension take in Hounslow?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Hounslow, and the guide-price tool gives a range for your own size and finish in about a minute.
Do I need planning permission for an extension in Hounslow?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
Book a free site visit in Hounslow
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.