Covering Greenwich
Greenwich sits 5 miles east of London, with Blackheath 1 miles to the south-east and Catford 2 miles to the south.
Homes in London
Much of London’s housing is Victorian and Edwardian terraces, which is why side return extensions, rear dormers and mansards are so common. Many streets are in conservation areas, and several boroughs use Article 4 directions that remove some permitted development rights.
What is a basement conversion?
Everything below ground depends on keeping water out. We design the waterproofing system (usually a cavity drain membrane with a pump, or tanking) to the relevant British Standard guidance, then add insulation, ventilation, light and an escape route. New basements involve underpinning and a party wall process and are designed with a structural engineer.
- Damp and structural survey
- Underpinning or lowering the floor where needed
- Ventilation, heating and electrics
What will a basement conversion cost?
Indicative costs for basement and cellar conversions. London and the South East usually sit towards the top of each range.
| Basement and cellar conversions | Guide price incl. VAT |
|---|---|
| Existing cellar conversion | £1,900 to £3,000 per m² |
| New basement excavation | £4,200 to £6,600 per m² |
How is a basement conversion approved in Greenwich?
English projects need planning clearance from the local council, building regulations sign-off from building control, and party wall notices where the work is on or near a shared boundary. We prepare and manage all three.
Converting an existing cellar with no external changes usually does not need planning permission in England.
What should I think about before starting?
- Groundwater levels drive the waterproofing design and cost.
- New basements nearly always involve the Party Wall Act in England and Wales.
What are the steps?
- Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
- Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
- Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
- Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.
Your questions answered
Does a cellar conversion need planning permission?
Usually not if nothing changes outside. New basements and lightwells often do.
How long does it take?
About 6 to 12 weeks for a cellar conversion and 16 to 30 weeks for a new basement.
Do you work in Greenwich?
Yes. Greenwich is within our coverage for basement and cellar conversions, along with nearby Blackheath and Catford.
Other towns nearby
- Basement and cellar conversions in Blackheath
- Basement and cellar conversions in Catford
- Basement and cellar conversions in Peckham
- Basement and cellar conversions in Canning Town
Learn more about basement and cellar conversions, or see every project we cover in Greenwich.