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 Wrexham?
In Wrexham, a basement conversion typically costs £1,750–£2,950 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £52,500–£88,500. The guide for Wrexham reflects typical costs in Wales, roughly 8% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £37,000–£62,000 |
| Typical project (30 m²) | £52,500–£88,500 |
| Larger project (42 m²) | £73,500–£124,000 |
| Rate per m² | £1,750–£2,950 |
Your quote will depend mainly on:
- Lightwells
- Floor lowering and underpinning
- Ground water and access
- Waterproofing system
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 Wrexham?
The approval route for Wrexham is set by planning law in Wales. In Wales converting an existing cellar usually does not need planning permission; new excavation and lightwells may.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
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:
- Waterproofing design (tanking or cavity drain membrane)
- Electrics, heating and plastering
- Structural and ground survey
- Underpinning or new structure where needed
- Building control sign-off
- 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. Before that, surveys, drawings and approvals usually take 3 to 5 months, longer if the council asks for changes.
Building in Wrexham
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Wrexham sits in Clwyd. We cover the whole of Wrexham, including postcodes LL13.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about basement conversions in Wrexham
How long does a basement conversion take in Wrexham?
Typically 8 to 16 weeks for a cellar conversion; longer for new excavation. Design and approvals beforehand usually take 3 to 5 months.
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 I need planning permission for a basement conversion in Wrexham?
In Wales converting an existing cellar usually does not need planning permission; new excavation and lightwells may.
How much does a basement conversion cost in Wrexham?
In Wrexham, a basement conversion typically costs £1,750–£2,950 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £52,500–£88,500. Your fixed price depends on the survey and drawings.
Is new excavation worth it?
It can be in high-value areas, but costs are high. We give a feasibility view before design starts.
Can a basement be a bedroom?
Yes, with a suitable escape route such as a lightwell window or protected stair.