Isleworth, Greater London
Glazed rear extension in Isleworth
For homes in Isleworth, a glazed rear extension is often the simplest way to gain space without moving. Full-height glass, slim frames and big rooflights for the most open rear room. We take it from survey to completion certificate.
Isleworth is covered from our Greater London round, including TW3, TW5 and TW7. A wide sliding door with one long rooflight, rather than a fully glazed roof, keeps a glass-led extension usable in summer.
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 glazed rear extension cost in Isleworth?
A glazed rear extension in Isleworth is priced at £3,640–£6,240 per square metre including VAT as a guide, before kitchen fit-out and fees. 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 wide × 4 m deep (12 m²) | £43,500–£75,000 |
| 4 m wide × 6 m deep (24 m²) | £87,500–£150,000 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a glazed rear extension in Isleworth?
Planning for a glazed rear extension in Isleworth follows the English householder rules.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
New fabric must meet Approved Document L (2021 edition incorporating 2023 amendments): walls 0.18, roof 0.15 and floor 0.18 W/m²K, windows 1.4 W/m²K or Band B. Under the simple route, new windows, doors and rooflights should not exceed 25% of the extension floor area plus any openings removed; more glass is possible with a whole-house calculation.
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?
Much of Isleworth is 1920s and 1930s semis and short terraces with longer gardens than inner London, which suit full-width single-storey rear extensions. Parking suspensions, skip licences and controlled hours on residential streets shape the programme more than the build itself.
How a glazed rear extension in Isleworth comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Glazed rear extensions near Isleworth
From Isleworth, the nearest places we also cover are Osterley (0.6 miles) and Hounslow (0.9 miles).
- Glazed rear extension in Osterley
- Glazed rear extension in Hounslow
- Glazed rear extension in Heston
- Glazed rear extension in Brentford
- Glazed rear extension in Richmond
Other work in Isleworth:
FAQ
Glazed rear extension questions in Isleworth
Can you match the brick or stone on my Isleworth house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
Will a glass extension be too hot?
Not if it is designed for its orientation, with solar-control glass, shading and ventilation.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
How much does a glazed rear extension cost in Isleworth?
As a guide, £3,640–£6,240 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £43,500–£75,000 at that rate. Your written price follows the survey.
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.