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 Oswestry?
In Oswestry, 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. Prices in the West Midlands sit near the national average for this kind of work, and the range for Oswestry reflects that. 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 main things that change the cost:
- Lightwells
- Floor lowering and underpinning
- Existing cellar or new excavation
- Ground water and access
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a basement conversion in Oswestry?
Before anything is built in Oswestry, 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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
What we take care of:
- Underpinning or new structure where needed
- Structural and ground survey
- Lightwells and windows
- Insulation, ventilation and drainage pumps
- Party wall notices
- 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. Design and approvals come first and typically take 3 to 5 months, depending on the approval route.
Building in Oswestry
Across the West Midlands, inter-war and post-war semis make up much of the housing, giving good scope for two-storey side extensions and hip-to-gable lofts.
From SY11 outwards, we take on projects throughout Oswestry and the surrounding parts of Shropshire.
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 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
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about basement conversions in Oswestry
Is new excavation worth it?
It can be in high-value areas, but costs are high. We give a feasibility view before design starts.
Do you build basement conversions in Oswestry?
Yes. We build basement conversions across Oswestry, including postcodes SY11. Every project starts with a free home visit.
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 much does a basement conversion cost in Oswestry?
In Oswestry, 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.
How long does it take?
A cellar conversion takes around 8 to 16 weeks; new basements take longer.