Basement and cellar conversions in Grantham

Covering Grantham

Grantham sits 22 miles south of Lincoln, with Newark-on-Trent 13 miles to the north-west and Melton Mowbray 14 miles to the south-west.

Homes in the East Midlands

The East Midlands combines red-brick terraces in the cities with a lot of post-war and modern estate housing, so rear extensions, garage conversions and loft conversions are all common.

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
Waterproofing design and installation
Ventilation, heating and electrics

How much does a basement conversion cost in Grantham?

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

Planning and building rules in Grantham

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 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 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.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

What people ask before starting

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.

How long does it take?

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

Who deals with the council for a project in Grantham?

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

Also covering

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