Basement and cellar conversions in Feltham

Covering Feltham

We work in Feltham (TW13) and the places around it, including Hanworth, Ashford and Hounslow.

Homes in London

Terraced houses dominate many London neighbourhoods, so most projects involve shared walls, narrow access and a party wall process. Conservation areas are widespread, and some boroughs have their own mansard and basement guidance.

What does a basement conversion involve?

A basement conversion turns an existing cellar into dry, usable rooms, or excavates a new basement under a house. Converting an existing cellar is far simpler and cheaper than digging a new one, and often does not need planning permission.

Underpinning or lowering the floor where needed
Lightwells and windows for daylight and escape
Finished floors, walls and ceilings

What is the guide price for a basement conversion in Feltham?

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

What approvals does a basement conversion need in England?

Projects in England go through two separate checks. Planning (or confirmation that the work is permitted development) comes from the district, borough or unitary council, and building regulations approval comes from the council’s building control team or a registered building control approver. Where work touches a shared wall or digs near a neighbour’s foundations, the Party Wall etc. Act 1996 applies.

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 change the price or programme?

Groundwater levels drive the waterproofing design and cost.
A pump for the drainage system needs a battery back-up.

What happens after I enquire?

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.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

Your questions answered

Does a cellar conversion need planning permission?

Usually not if nothing changes outside. New basements and lightwells often do.

Will my neighbours be affected?

New basements usually need party wall agreements. We handle the notices and surveyors.

Who deals with the council for a project in Feltham?

We do. We prepare the drawings, submit planning or permitted development paperwork if needed, and arrange building control inspections.

Basement and cellar conversions in nearby towns

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