Dormer loft conversions in Isleworth

Covering Isleworth

Isleworth is about 10 miles west of London. We also cover Hounslow (1 miles to the south-west), Heston and Richmond.

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 does a dormer loft conversion involve?

Rear dormers on terraced and semi-detached houses are often permitted development in England. We size the dormer to fit the volume allowance, clad it to suit the house (tile-hanging, render, slate or zinc) and fit out the room and en-suite below.

Volume calculation and permitted development check
Staircase, insulation and plasterboard
En-suite, electrics and fire-protected escape route

How much should I budget for a dormer loft conversion?

What dormer loft conversions typically cost. These are guide ranges; the written quote for your house replaces them.

Dormer loft conversions	Guide price incl. VAT
Rear dormer, bedroom only	£50,000 to £65,000
Full-width dormer with en-suite	£60,000 to £80,000
L-shaped dormer (over rear outrigger)	£65,000 to £90,000

How is a dormer loft conversion approved in Isleworth?

English projects need planning clearance from the local council, building regulations sign-off from building control, and party wall notices where the work is on or near a shared boundary. We prepare and manage all three.

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.

What should I think about before starting?

Dormers on the front of the house facing a road are not permitted development in England.
Dormer cheeks close to a shared wall can trigger the Party Wall Act.

What are the steps?

Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
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.

Dormer loft conversions: common questions

Is a dormer permitted development?

Rear dormers in England often are, within the 40 m³ (terrace) or 50 m³ (semi or detached) volume allowance. Front dormers facing a road are not.

How long does a dormer conversion take?

Around 8 to 12 weeks on site.

How do I get a price for dormer loft conversions in Isleworth?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Other towns nearby

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