Covering Cardiff
Alongside Cardiff, we also cover Whitchurch (3 miles to the north-west), Penarth and Caerphilly.
Homes in South Glamorgan
Welsh homes include long terraces built into hillsides, stone cottages and modern estates, and sloping sites often shape how and where an extension can go.
What is 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.
- Structural design and party wall process
- Staircase, insulation and fit-out
- En-suite, electrics and fire safety
How much should I budget for a mansard loft conversion?
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 Cardiff?
In Wales the planning rules, including what counts as permitted development, are set by the Welsh Government, and Welsh building regulations differ in places from England’s. We check both against your house before drawings are finalised, and handle party wall notices where needed.
This needs full planning permission from your council in Wales.
What can affect a mansard loft conversion?
- The roof is open for longer than with a dormer, so weather protection matters.
- Scaffolding and a temporary roof are usually needed.
From first call to completion
- Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
- 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.
- Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.
Mansard loft conversions: common questions
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.
Why choose a mansard over a dormer?
A mansard gives more usable space and often fits a street better where neighbours already have one.
Can you visit a house in Cardiff to quote?
Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.
Mansard loft conversions near Cardiff
- Mansard loft conversions in Whitchurch
- Mansard loft conversions in Penarth
- Mansard loft conversions in Caerphilly
- Mansard loft conversions in Barry
Learn more about mansard loft conversions, or see every project we cover in Cardiff.