Mansard loft conversions in Chelsea

Covering Chelsea

Our coverage around Chelsea (SW3, SW10) also includes Battersea, Fulham and Notting Hill.

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 goes into 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
Slate cladding and lead-clad dormers
Staircase, insulation and fit-out

How much does a mansard loft conversion cost in Chelsea?

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

Mansard loft conversions	Guide price incl. VAT
Rear mansard	£65,000 to £85,000
Front and rear (double) mansard	£80,000 to £110,000

What approvals does a mansard loft conversion need in England?

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.

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?

Council design guides often require natural slate and lead.
Scaffolding and a temporary roof are usually needed.

How does the project run?

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.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

What people ask before starting

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.

Does a mansard need planning permission?

Almost always, because it changes the roof profile.

Do you work in Chelsea?

Yes. Chelsea is within our coverage for mansard loft conversions, along with nearby Battersea and Fulham.

Mansard loft conversions near Chelsea

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