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 Hull?
In Hull, a basement conversion typically costs £1,750–£3,000 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £52,500–£90,000. Building costs in Yorkshire and the Humber run about 7% below the UK average, and the figures for Hull are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £37,000–£63,000 |
| Typical project (30 m²) | £52,500–£90,000 |
| Larger project (42 m²) | £73,500–£126,000 |
| Rate per m² | £1,750–£3,000 |
Your quote will depend mainly on:
- Party wall surveyor fees
- Waterproofing system
- Existing cellar or new excavation
- Ground water and access
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 Hull?
Whether you need planning permission depends on your house and its location 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
The work we manage on a basement conversion:
- Underpinning or new structure where needed
- Party wall notices
- Structural and ground survey
- Waterproofing design (tanking or cavity drain membrane)
- Building control sign-off
- Electrics, heating and plastering
How long does it take?
Build time is typically 8 to 16 weeks for a cellar conversion; longer for new excavation. Allow time beforehand for drawings and approvals, usually 3 to 5 months.
Building in Hull
In Yorkshire, through-terraces and back-to-backs have particular constraints, while semis and detached houses suit larger extensions.
If your home is in Hull or close by in Beverley, Brough and Grimsby, a free home visit is the first step.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about basement conversions in Hull
Do you build basement conversions in Hull?
Yes. We build basement conversions across Hull, including postcodes HU2, HU3, HU4 and HU5. Every project starts with a free home visit.
How much does a basement conversion cost in Hull?
In Hull, a basement conversion typically costs £1,750–£3,000 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £52,500–£90,000. Your fixed price depends on the survey and drawings.
Do I need party wall agreements?
In England and Wales, excavating near a neighbour’s foundations usually triggers the Party Wall etc. Act 1996.
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.