What is a basement conversion?
A basement conversion turns an existing cellar into living space, or excavates a new basement under the house or garden. Waterproofing, structural support and daylight are the main design challenges.
How much does a basement conversion cost in St Neots?
In St Neots, a basement conversion typically costs £2,000–£3,400 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £60,000–£102,000. The guide for St Neots reflects typical costs in the East of England, roughly 6% above the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £42,000–£71,500 |
| Typical project (30 m²) | £60,000–£102,000 |
| Larger project (42 m²) | £84,000–£143,000 |
| Rate per m² | £2,000–£3,400 |
The main things that change the cost:
- Lightwells
- Waterproofing system
- Existing cellar or new excavation
- Floor lowering and underpinning
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a basement conversion in St Neots?
Here is how the rules work for a basement conversion in England. In England converting an existing cellar with no external change usually does not need planning permission. New excavation, lightwells and changes to the front often do, and some councils, particularly in London, have specific basement policies.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
Handled as part of most basement conversions:
- Underpinning or new structure where needed
- Party wall notices
- Building control sign-off
- Waterproofing design (tanking or cavity drain membrane)
- Electrics, heating and plastering
- Insulation, ventilation and drainage pumps
How long does it take?
Build time is typically 8 to 16 weeks for a cellar conversion; longer for new excavation. Design and approvals come first and typically take 3 to 5 months, depending on the approval route.
Building in St Neots
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
We work across St Neots and neighbouring areas such as Huntingdon, Bedford and Kempston. Postcodes we cover in St Neots include PE19.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about basement conversions in St Neots
How much does a basement conversion cost in St Neots?
In St Neots, a basement conversion typically costs £2,000–£3,400 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £60,000–£102,000. Your fixed price depends on the survey and drawings.
Who approves a basement conversion in St Neots?
Planning matters in St Neots go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Is new excavation worth it?
It can be in high-value areas, but costs are high. We give a feasibility view before design starts.
How do you keep a basement dry?
With a waterproofing system designed to BS 8102, typically a cavity drain membrane with a sump pump, or a tanking system.
How long does it take?
A cellar conversion takes around 8 to 16 weeks; new basements take longer.