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 West Yorkshire?
In West Yorkshire, a mansard loft conversion typically costs £60,500–£88,500 for a typical rear mansard, including VAT at 20% (standard rate). The guide for West Yorkshire reflects typical costs in Yorkshire and the Humber, roughly 7% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear mansard | £60,500–£88,500 |
| Higher specification | £88,500–£110,500 |
The biggest cost drivers are:
- Front, rear or both
- Party wall surveyor fees
- Roof covering: natural slate costs more
- Number of dormers and lead work
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a mansard loft conversion in West Yorkshire?
Before anything is built in West Yorkshire, we confirm which approvals apply 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
What we take care of:
- Insulation, electrics, plumbing and plastering
- Building control sign-off
- New roof structure, slate or tile covering and lead work
- Staircase and fire-safe escape route
- Party wall notices to both neighbours
- Dormer windows
How long does it take?
Allow 9 to 12 weeks on site, after planning approval. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in West Yorkshire
Yorkshire and the Humber has stone and brick terraces as well as inter-war and newer estates, so materials matching is an early design question.
Towns we cover in West Yorkshire include Leeds, Bradford, Huddersfield, Wakefield, Halifax and Dewsbury.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 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 handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about mansard loft conversions in West Yorkshire
Do you build mansard loft conversions in West Yorkshire?
Yes. We build mansard loft conversions across West Yorkshire, including postcodes BD1, BD10, BD11, BD12 and BD13. Every project starts with a free home visit.
How long does it take?
Around 9 to 12 weeks on site, plus 2 to 3 months for planning and party wall matters beforehand.
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.
How much does a mansard loft conversion cost in West Yorkshire?
In West Yorkshire, a mansard loft conversion typically costs £60,500–£88,500 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.
