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House Extensions in Isleworth
Extensions for Isleworth's Victorian, Edwardian and 1930s homes. Local team from nearby Hounslow, clear written quotes.
- Free site visit and feasibility check
- Conservation area and Permitted Development advice
- Architectural drawings and planning application to the London Borough of Hounslow
- Structural calculations and steel design
- Party Wall notices
- Building Regulations application and stage inspections
- Groundworks, foundations and masonry, including brick matching on older houses
- Roof, insulation and rooflights or lantern
- Glazed doors and windows
- Electrics, plumbing and heating
- Plastering, flooring and decoration
- Building Control completion certificate
Isleworth has a real mix of housing, and that changes how an extension should be designed. The Victorian and Edwardian houses around Spring Grove and Old Isleworth suit side return and rear extensions that respect the original building, while the interwar semis towards Osterley and Worton suit wider rear and wraparound extensions.
Parts of Isleworth sit in conservation areas, including Spring Grove and Old Isleworth. Permitted Development rights are more limited there, so getting the design and the planning application right first time matters. We prepare the drawings and handle the application to the London Borough of Hounslow for you.
We are based just down the road in Hounslow, so we can visit quickly and keep a close eye on your build.
Isleworth (TW7), Spring Grove, Old Isleworth, Osterley, Worton, St Margarets, Brentford, Hounslow, Twickenham
Conservation area experience matters. We design to suit the house and the planners, not just the floor area.
Fixed written quotes. Labour and materials set out line by line.
Close by in Hounslow. Quick site visits and hands-on supervision.
Rated 5 stars on Google. See our reviews on our Google profile.
Fully insured. Public liability cover on every project.
How much does a house extension cost in Isleworth?
Most extensions cost between £1,800 and £2,800 per square metre. A 20 to 25 square metre rear or side return extension usually costs £35,000 to £60,000. Period houses that need matching brick or detailing can sit towards the top of that range.
My house is in a conservation area. Can I still extend?
Usually yes, but with fewer Permitted Development rights, so most extensions need full planning permission. Rear extensions that keep to the character of the house are often approved. We advise on this at the site visit.
How long does an extension take?
Allow about 8 weeks for planning, then 12 to 18 weeks on site depending on size.
Do you cover Isleworth regularly?
Yes. We are based in neighbouring Hounslow, and Isleworth is part of our core area.
Book a free site visit and get a fixed written quote. We cover Isleworth, Spring Grove, Osterley, St Margarets, Brentford and Hounslow. We reply within 1 working day.