Covering Boston
Boston sits 27 miles south-east of Lincoln, with Spalding 14 miles to the south and Skegness 19 miles to the north-east.
Homes in the East Midlands
Across the East Midlands you find everything from city terraces to modern estates and stone villages, so the right extension depends a lot on the street and the materials around it.
What does a mansard loft conversion involve?
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.
- Planning application to local design guidance
- Structural design and party wall process
- Roof removal and new mansard frame
How much should I budget for a mansard loft conversion?
What mansard loft conversions typically cost. These are guide ranges; the written quote for your house replaces them.
| Mansard loft conversions | Guide price incl. VAT |
|---|---|
| Rear mansard | £65,000 to £85,000 |
| Front and rear (double) mansard | £80,000 to £110,000 |
Do you need permission for a mansard loft conversion in Boston?
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?
- The roof is open for longer than with a dormer, so weather protection matters.
- Scaffolding and a temporary roof are usually needed.
What happens after I enquire?
- 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.
- 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.
Questions about a mansard loft conversion in Boston
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.
How long does a mansard take?
Around 10 to 14 weeks on site after planning approval.
How do I get a price for mansard loft conversions in Boston?
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 Spalding
- Mansard loft conversions in Skegness
- Mansard loft conversions in Wisbech
- Mansard loft conversions in King's Lynn
Learn more about mansard loft conversions, or see every project we cover in Boston.

