Basement and cellar conversions in Dorset

Covering Dorset

Our coverage across Dorset includes Bournemouth, Poole, Weymouth and Christchurch.

Homes in the South West

In the South West, matching local stone, render or slate is often the main design question, and conservation areas and listed buildings are common in historic towns.

What is included in a basement conversion in Dorset?

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
Finished floors, walls and ceilings

What will a basement conversion cost?

What basement and cellar conversions typically cost. These are guide ranges; the written quote for your house replaces them.

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?

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?

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?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
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

Does a cellar conversion need planning permission?

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

How do you keep a basement dry?

With a designed waterproofing system, usually a cavity drain membrane draining to a pump, sometimes combined with tanking.

Who deals with the council for a project in Dorset?

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 Dorset.