Mansard loft conversions in St Austell

Covering St Austell

We work in St Austell (PL25) and the places around it, including Bodmin, Truro and Falmouth.

Projects in Cornwall are taken on by arrangement, and any travel and accommodation costs for the team are shown openly in the quote.

Homes in the South West

The South West mixes stone and render cottages, Victorian terraces in the larger towns and modern estates, and many historic centres are conservation areas where materials and roof shapes are closely controlled.

What do you get with 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
Roof removal and new mansard frame
Staircase, insulation and fit-out

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

What approvals does a mansard loft conversion need in England?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

Mansard conversions change the shape of the roof significantly, so they usually need planning permission in England. Many councils publish guidance on mansard design.

What can change the price or programme?

The roof is open for longer than with a dormer, so weather protection matters.
Scaffolding and a temporary roof are usually needed.

How does the project run?

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.
Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

Your questions answered

Does a mansard need planning permission?

Almost always, because it changes the roof profile.

Will I need party wall agreements?

Very likely, as the work affects the walls shared with both neighbours on a terrace.

How do I get a price for mansard loft conversions in St Austell?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Other towns nearby

Learn more about mansard loft conversions, or see every project we cover in St Austell.