What is a mansard loft conversion?
A mansard loft conversion rebuilds the roof with a nearly vertical slope (about 72 degrees) and a flat top, effectively adding a new storey. Small dormer windows sit within the steep slope. Mansards are common on period terraces in towns and cities.
How much does a mansard loft conversion cost in Chichester?
In Chichester, a mansard loft conversion typically costs £73,000–£106,500 for a typical rear mansard, including VAT at 20% (standard rate). We start from a UK-wide guide and adjust it for the South East, where labour and materials are typically about 12% above average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear mansard | £73,000–£106,500 |
| Higher specification | £106,500–£133,000 |
The biggest cost drivers are:
- Number of dormers and lead work
- Roof covering: natural slate costs more
- Party wall surveyor fees
- Bathrooms and finishes
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a mansard loft conversion in Chichester?
The approval route for Chichester is set by planning law in England. In England a mansard almost always needs planning permission because it changes the roof shape. Many councils publish design guidance for mansards on terraced streets, and some streets are more likely to be approved where neighbours already have one.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Planning drawings and application
- Building control sign-off
- New roof structure, slate or tile covering and lead work
- Insulation, electrics, plumbing and plastering
- Dormer windows
- Staircase and fire-safe escape route
How long does it take?
The build itself usually takes 9 to 12 weeks on site, after planning approval. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Chichester
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
From PO19 outwards, we take on projects throughout Chichester and the surrounding parts of West Sussex.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about mansard loft conversions in Chichester
Do I need party wall agreements?
Yes, mansards on terraced houses almost always involve both party walls.
How much does a mansard loft conversion cost in Chichester?
In Chichester, a mansard loft conversion typically costs £73,000–£106,500 for a typical rear mansard, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do you build mansard loft conversions in Chichester?
Yes. We build mansard loft conversions across Chichester, including postcodes PO19. Every project starts with a free home visit.
Why choose a mansard over a dormer?
A mansard gives more usable floor space and a neater appearance from the street, but costs more and needs planning permission.
Does a mansard need planning permission?
Almost always, because it changes the roof shape. Councils assess it against local design guidance.