Basement and cellar conversions in Hemel Hempstead

Covering Hemel Hempstead

Hemel Hempstead is about 5 miles west of St Albans. We also cover Berkhamsted (5 miles to the west), St Albans and Harpenden.

Homes in the East of England

Housing in the East of England ranges from post-war estates and modern developments to timber-framed and period homes in historic towns, so permitted development checks and conservation controls both feature regularly.

What does a basement conversion involve?

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
Waterproofing design and installation
Lightwells and windows for daylight and escape

How much should I budget for a basement conversion?

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

How is a basement conversion approved in Hemel Hempstead?

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 can change the price or programme?

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.

From first call to completion

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

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.

Will my neighbours be affected?

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

Do you work in Hemel Hempstead?

Yes. Hemel Hempstead is within our coverage for basement and cellar conversions, along with nearby Berkhamsted and St Albans.

Other towns nearby

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