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 Erskine?
In Erskine, 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 Scotland sit near the national average for this kind of work, and the range for Erskine 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:
- Waterproofing system
- Lightwells
- Ground water and access
- Floor lowering and underpinning
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a basement conversion in Erskine?
Whether you need planning permission depends on your house and its location in Scotland. In Scotland converting an existing cellar may not need planning permission, but a building warrant is needed, and new excavation usually needs planning permission.
Scotland has no Party Wall Act. Work on shared walls is governed by your title deeds, the Tenements (Scotland) Act 2004 for flats, and common law, so we agree arrangements with neighbours in writing before work starts.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
On a typical basement conversion we handle:
- Insulation, ventilation and drainage pumps
- Electrics, heating and plastering
- Building control sign-off
- Lightwells and windows
- Written agreement with neighbours on shared walls
- Underpinning or new structure where needed
How long does it take?
Allow 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 Erskine
Scotland’s housing ranges from sandstone tenements and villas to post-war and modern estates, and the building warrant system shapes how projects are planned.
Erskine sits in Renfrewshire and Inverclyde, about 5 miles north of Paisley. We cover the whole of Erskine, including postcodes PA8.
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 Erskine
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 Erskine?
In Erskine, 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.
Who approves a basement conversion in Erskine?
Planning matters in Erskine go to the council covering your address, and the work needs a building warrant. We prepare and submit the applications for you.
Can a basement be a bedroom?
Yes, with a suitable escape route such as a lightwell window or protected stair.
How long does it take?
A cellar conversion takes around 8 to 16 weeks; new basements take longer.
Do I need planning permission for a basement conversion in Erskine?
In Scotland converting an existing cellar may not need planning permission, but a building warrant is needed, and new excavation usually needs planning permission.
