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 Stratford?
In Stratford, a mansard loft conversion typically costs £84,500–£123,500 for a typical rear mansard, including VAT at 20% (standard rate). Building costs in London run about 30% above the UK average, and the figures for Stratford are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear mansard | £84,500–£123,500 |
| Higher specification | £123,500–£154,500 |
What moves the price most:
- Bathrooms and finishes
- Party wall surveyor fees
- Scaffolding on busy streets
- Number of dormers and lead work
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a mansard loft conversion in Stratford?
The approval route for Stratford is set by planning law 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
On a typical mansard loft conversion we handle:
- New roof structure, slate or tile covering and lead work
- Dormer windows
- Structural design and calculations
- Staircase and fire-safe escape route
- Insulation, electrics, plumbing and plastering
- Building control sign-off
How long does it take?
Expect 9 to 12 weeks on site, after planning approval. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Stratford
Space is at a premium in London, so homeowners often build out into the side return or up into the roof rather than move.
If your home is in Stratford or close by in Bow, Leyton and Hackney, a free home visit is the first step.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 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 Stratford
What roof covering is used?
Natural slate is traditional; some councils accept other materials. We follow local guidance.
Do I need party wall agreements?
Yes, mansards on terraced houses almost always involve both party walls.
Who approves a mansard loft conversion in Stratford?
Planning matters in Stratford go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much does a mansard loft conversion cost in Stratford?
In Stratford, a mansard loft conversion typically costs £84,500–£123,500 for a typical rear mansard, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.