Covering Seaham
We work in Seaham (SR7) and the places around it, including Houghton-le-Spring, Sunderland and Washington.
Homes in the North East
In the North East, terraces, semis and bungalows all offer room to extend, with stone-built villages and conservation areas in parts of County Durham and Northumberland.
What goes into 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
How much should I budget for a mansard loft conversion?
Indicative costs for mansard loft conversions. London and the South East usually sit towards the top of each range.
| Mansard loft conversions | Guide price incl. VAT |
|---|---|
| Rear mansard | £65,000 to £85,000 |
| Front and rear (double) mansard | £80,000 to £110,000 |
Planning and building rules in Seaham
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 should I think about before starting?
- Council design guides often require natural slate and lead.
- Scaffolding and a temporary roof are usually needed.
From first call to completion
- Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
- Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
- Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
- Construction and completion. One site lead co-ordinates every trade through to the building control certificate.
What people ask before starting
Does a mansard need planning permission?
Almost always, because it changes the roof profile.
Why choose a mansard over a dormer?
A mansard gives more usable space and often fits a street better where neighbours already have one.
How do I get a price for mansard loft conversions in Seaham?
Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.
Also covering
- Mansard loft conversions in Houghton-le-Spring
- Mansard loft conversions in Sunderland
- Mansard loft conversions in Washington
- Mansard loft conversions in Chester-le-Street
Learn more about mansard loft conversions, or see every project we cover in Seaham.

