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 Woolwich?
In Woolwich, a mansard loft conversion typically costs £84,500–£123,500 for a typical rear mansard, including VAT at 20% (standard rate). The guide for Woolwich reflects typical costs in London, roughly 30% above the UK-wide figure. 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 |
The biggest cost drivers are:
- Scaffolding on busy streets
- Bathrooms and finishes
- Roof covering: natural slate costs more
- Party wall surveyor fees
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a mansard loft conversion in Woolwich?
Before anything is built in Woolwich, we confirm which approvals apply 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
The work we manage on a mansard loft conversion:
- Dormer windows
- New roof structure, slate or tile covering and lead work
- Structural design and calculations
- Party wall notices to both neighbours
- Building control sign-off
- Staircase and fire-safe escape route
How long does it take?
The build itself usually takes 9 to 12 weeks on site, after planning approval. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Woolwich
Space is at a premium in London, so homeowners often build out into the side return or up into the roof rather than move.
Woolwich sits in Greater London, about 8 miles east of central London. We cover the whole of Woolwich, including postcodes SE18.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about mansard loft conversions in Woolwich
How much does a mansard loft conversion cost in Woolwich?
In Woolwich, 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.
Do I need party wall agreements?
Yes, mansards on terraced houses almost always involve both party walls.
Does a mansard need planning permission?
Almost always, because it changes the roof shape. Councils assess it against local design guidance.
How long does a mansard loft conversion take in Woolwich?
Typically 9 to 12 weeks on site, after planning approval. Design and approvals beforehand usually take 3 to 4 months.
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.