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 Aldridge?
In Aldridge, a basement conversion typically costs £1,850–£3,100 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £55,500–£93,000. Building costs in the West Midlands are close to the UK average, so the figures for Aldridge are close to our national guide. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £39,000–£65,000 |
| Typical project (30 m²) | £55,500–£93,000 |
| Larger project (42 m²) | £77,500–£130,000 |
| Rate per m² | £1,850–£3,100 |
The biggest cost drivers are:
- Ground water and access
- Existing cellar or new excavation
- Waterproofing system
- Party wall surveyor fees
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 Aldridge?
Before anything is built in Aldridge, we confirm which approvals apply 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
The work we manage on a basement conversion:
- Underpinning or new structure where needed
- Insulation, ventilation and drainage pumps
- Structural and ground survey
- Electrics, heating and plastering
- Party wall notices
- Lightwells and windows
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 Aldridge
The West Midlands has large numbers of 1930s semis and Victorian terraces, which suit rear extensions, side extensions and dormer loft conversions.
We work across Aldridge and neighbouring areas such as Walsall, Bloxwich and Sutton Coldfield. Postcodes we cover in Aldridge include WS9.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 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 Aldridge
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 long does it take?
A cellar conversion takes around 8 to 16 weeks; new basements take longer.
Who approves a basement conversion in Aldridge?
Planning matters in Aldridge go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much does a basement conversion cost in Aldridge?
In Aldridge, a basement conversion typically costs £1,850–£3,100 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £55,500–£93,000. 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.
