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 Fareham?
In Fareham, a mansard loft conversion typically costs £73,000–£106,500 for a typical rear mansard, including VAT at 20% (standard rate). The guide for Fareham reflects typical costs in the South East, roughly 12% above the UK-wide figure. 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 |
Your quote will depend mainly on:
- Front, rear or both
- Party wall surveyor fees
- Scaffolding on busy streets
- Roof covering: natural slate costs more
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a mansard loft conversion in Fareham?
The approval route for Fareham 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
What we take care of:
- Staircase and fire-safe escape route
- Party wall notices to both neighbours
- Dormer windows
- New roof structure, slate or tile covering and lead work
- Planning drawings and application
- Structural design and calculations
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 Fareham
Commuter towns across the South East have many 1930s and post-war semis that suit rear extensions and hip-to-gable loft conversions.
If your home is in Fareham or close by in Gosport, Portsmouth and Southsea, a free home visit is the first step.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about mansard loft conversions in Fareham
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.
How much does a mansard loft conversion cost in Fareham?
In Fareham, 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.
What roof covering is used?
Natural slate is traditional; some councils accept other materials. We follow local guidance.
Does a mansard need planning permission?
Almost always, because it changes the roof shape. Councils assess it against local design guidance.
How long does a mansard loft conversion take in Fareham?
Typically 9 to 12 weeks on site, after planning approval. Design and approvals beforehand usually take 3 to 4 months.
