Mansard loft conversions in West Sussex

Covering West Sussex

Our coverage across West Sussex includes Crawley, Worthing, Bognor Regis and Littlehampton.

Homes in the South East

The South East has a lot of 1930s and post-war semi-detached housing, well suited to rear extensions and hip-to-gable loft conversions, alongside period properties in conservation areas that need a more careful design.

What do you get with 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.

Slate cladding and lead-clad dormers
Staircase, insulation and fit-out
En-suite, electrics and fire safety

What is the guide price for a mansard loft conversion in West Sussex?

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

How is a mansard loft conversion approved in West Sussex?

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.

What can change the price or programme?

A mansard nearly always involves party walls on both sides of a terrace.
Council design guides often require natural slate and lead.

What are the steps?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

Questions about a mansard loft conversion in West Sussex

Does a mansard need planning permission?

Almost always, because it changes the roof profile.

Will I need party wall agreements?

Very likely, as the work affects the walls shared with both neighbours on a terrace.

Who deals with the council for a project in West Sussex?

We do. We prepare the drawings, submit planning or permitted development paperwork if needed, and arrange building control inspections.

Also covering

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