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
London projects often mean working on period terraces with neighbours on both sides, tight access through the house and conservation area controls, so careful planning and party wall work matter as much as the build.
What is a mansard loft conversion?
A mansard loft conversion replaces one or both slopes of a roof with a near-vertical wall, typically at 70 degrees, with small dormer windows set into it. It creates almost a full extra storey and is common on terraced houses in towns and cities, particularly in London.
- Planning application to local design guidance
- Structural design and party wall process
- Slate cladding and lead-clad dormers
What will a mansard loft conversion cost?
Use these ranges to budget for mansard loft conversions; the survey turns them into a fixed price for the agreed specification.
| Mansard loft conversions | Guide price incl. VAT |
|---|---|
| Rear mansard | £65,000 to £85,000 |
| Front and rear (double) mansard | £80,000 to £110,000 |
Planning and building rules 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.
Mansard conversions change the shape of the roof significantly, so they usually need planning permission in England. Many councils publish guidance on mansard design.
What should I think about before starting?
- The roof is open for longer than with a dormer, so weather protection matters.
- Council design guides often require natural slate and lead.
From first call to completion
- 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.
- Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
- We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.
Your questions answered
How much does a mansard loft conversion cost?
Typically £65,000 to £110,000 including VAT, depending on whether one or both roof slopes are rebuilt.
How long does a mansard take?
Around 10 to 14 weeks on site after planning approval.
Do you work in Isleworth?
Yes. Isleworth is within our coverage for mansard loft conversions, along with nearby Hounslow and Heston.
Mansard loft conversions near Isleworth
- Mansard loft conversions in Hounslow
- Mansard loft conversions in Heston
- Mansard loft conversions in Richmond
- Mansard loft conversions in Southall
Learn more about mansard loft conversions, or see every project we cover in Isleworth.