Loft conversions in Isleworth

Covering Isleworth

Isleworth sits 10 miles west of London, with Hounslow 1 miles to the south-west and Heston 2 miles to the west.

Homes in London

Much of London’s housing is Victorian and Edwardian terraces, which is why side return extensions, rear dormers and mansards are so common. Many streets are in conservation areas, and several boroughs use Article 4 directions that remove some permitted development rights.

What do you get with a loft conversion?

A loft conversion turns an unused roof space into habitable rooms, usually a bedroom with an en-suite, by strengthening the floor, adding a staircase, insulating the roof and putting in windows. The type you need depends on the roof: rooflight, dormer, hip-to-gable or mansard.

Planning or lawful development certificate
New floor joists, steels and staircase
Dormer or rooflights, insulation and plasterboard

How much does a loft conversion cost in Isleworth?

Indicative costs for loft conversions. London and the South East usually sit towards the top of each range.

Loft conversions	Guide price incl. VAT
Rooflight conversion	£30,000 to £45,000
Dormer conversion	£50,000 to £90,000
Hip-to-gable with dormer	£60,000 to £95,000
Mansard conversion	£65,000 to £110,000

Planning and building rules in Isleworth

Projects in England go through two separate checks. Planning (or confirmation that the work is permitted development) comes from the district, borough or unitary council, and building regulations approval comes from the council’s building control team or a registered building control approver. Where work touches a shared wall or digs near a neighbour’s foundations, the Party Wall etc. Act 1996 applies.

In England many loft conversions are permitted development: the extra roof volume must stay within 40 m³ on a terraced house or 50 m³ on a semi or detached house, nothing can sit higher than the existing ridge, no dormer can face a road on the main elevation, and side windows must be obscure-glazed and non-opening below 1.7 m. Houses in conservation areas, National Parks and National Landscapes cannot use these roof-extension rights, so dormers there need planning permission (a rooflight-only conversion can still be permitted development), and flats always need permission.

What can change the price or programme?

Head height under the ridge decides whether a conversion is practical.
The new staircase usually takes space from the landing or a bedroom below.

What are the steps?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

Loft conversions: common questions

Can we live at home during a loft conversion?

Yes. Most of the work is done from scaffolding until the staircase goes in near the end.

Do I need fire doors?

Often yes. Building regulations require a protected escape route from the new floor, which usually means fire doors on to the stairs and linked smoke alarms.

Can you visit a house in Isleworth to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Loft conversions in nearby towns

Learn more about loft conversions, or see every project we cover in Isleworth.