Basement and cellar conversions in Hanworth

Covering Hanworth

We work in Hanworth (TW13) and the places around it, including Feltham, Sunbury-on-Thames and Hounslow.

Homes in London

London projects often mean working on period terraces with neighbours on both sides, tight access through the house and conservation area controls, so careful planning and party wall work matter as much as the build.

What do you get with 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

How much does a basement conversion cost in Hanworth?

Use these ranges to budget for basement and cellar conversions; the survey turns them into a fixed price for the agreed specification.

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

Planning and building rules in Hanworth

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. Digging a new basement or adding a lightwell often does, and many councils have basement policies.

What can affect a basement conversion?

A pump for the drainage system needs a battery back-up.
Headroom of about 2.1 m or more is needed, which may mean lowering the floor.

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.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Basement and cellar conversions: common questions

How much does a basement conversion cost?

Converting an existing cellar costs about £1,900 to £3,000 per square metre including VAT. A new excavated basement is around £4,200 to £6,600 per square metre.

How long does it take?

About 6 to 12 weeks for a cellar conversion and 16 to 30 weeks for a new basement.

Can you visit a house in Hanworth to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Basement and cellar conversions near Hanworth

Learn more about basement and cellar conversions, or see every project we cover in Hanworth.