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 Bedford?
In Bedford, 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. Building costs in the East of England run about 6% above the UK average, and the figures for Bedford are adjusted to reflect that. 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:
- Existing cellar or new excavation
- Lightwells
- Floor lowering and underpinning
- Ground water and access
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a basement conversion in Bedford?
The approval route for Bedford is set by planning law 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:
- Structural and ground survey
- Electrics, heating and plastering
- Lightwells and windows
- Party wall notices
- Building control sign-off
- Underpinning or new structure where needed
How long does it take?
Expect 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 Bedford
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
Projects in Bedford (MK40) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about basement conversions in Bedford
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 much does a basement conversion cost in Bedford?
In Bedford, 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.
Can a basement be a bedroom?
Yes, with a suitable escape route such as a lightwell window or protected stair.
Does a basement conversion need planning permission?
Converting an existing cellar without changing the outside usually does not. New excavation, lightwells and changes visible from outside usually do.
Do you build basement conversions in Bedford?
Yes. We build basement conversions across Bedford, including postcodes MK40. Every project starts with a free home visit.