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 Ashington?
In Ashington, a basement conversion typically costs £1,700–£2,900 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £51,000–£87,000. We start from a UK-wide guide and adjust it for the North East, where labour and materials are typically about 10% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £35,500–£61,000 |
| Typical project (30 m²) | £51,000–£87,000 |
| Larger project (42 m²) | £71,500–£122,000 |
| Rate per m² | £1,700–£2,900 |
What moves the price most:
- Lightwells
- Waterproofing system
- Existing cellar or new excavation
- Party wall surveyor fees
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 Ashington?
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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
What we take care of:
- Building control sign-off
- Lightwells and windows
- Underpinning or new structure where needed
- Electrics, heating and plastering
- Party wall notices
- Structural and ground survey
How long does it take?
The build itself usually takes 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 Ashington
The North East has many terraced streets and post-war semis, where rear extensions and loft conversions are popular ways to gain space.
We work across Ashington and neighbouring areas such as Bedlington, Blyth and Cramlington. Postcodes we cover in Ashington include NE63.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about basement conversions in Ashington
How long does it take?
A cellar conversion takes around 8 to 16 weeks; new basements take longer.
How much does a basement conversion cost in Ashington?
In Ashington, a basement conversion typically costs £1,700–£2,900 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £51,000–£87,000. Your fixed price depends on the survey and drawings.
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.
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.
Do you build basement conversions in Ashington?
Yes. We build basement conversions across Ashington, including postcodes NE63. Every project starts with a free home visit.