Covering Cardiff
We work in Cardiff (CF10, CF11, CF14) and the places around it, including Whitchurch, Penarth and Caerphilly.
Homes in South Glamorgan
Across Wales you find valley terraces, coastal towns, rural stone houses and newer estates, so access, slopes and local materials all feature in the design.
What is included in a basement conversion in Cardiff?
Everything below ground depends on keeping water out. We design the waterproofing system (usually a cavity drain membrane with a pump, or tanking) to the relevant British Standard guidance, then add insulation, ventilation, light and an escape route. New basements involve underpinning and a party wall process and are designed with a structural engineer.
- Damp and structural survey
- Waterproofing design and installation
- Finished floors, walls and ceilings
What is the guide price for a basement conversion in Cardiff?
What basement and cellar conversions typically cost. These are guide ranges; the written quote for your house replaces them.
| Basement and cellar conversions | Guide price incl. VAT |
|---|---|
| Existing cellar conversion | £1,900 to £3,000 per m² |
| New basement excavation | £4,200 to £6,600 per m² |
Planning and building rules in Cardiff
Welsh projects need planning clearance from the council under Welsh rules, building regulations approval under the Welsh approved documents, and party wall notices where the work affects a neighbour’s wall or foundations.
In Wales an existing cellar conversion usually does not need planning permission; new excavation and lightwells may.
What should I think about before starting?
- A pump for the drainage system needs a battery back-up.
- Headroom of about 2.1 m or more is needed, which may mean lowering the floor.
How does the project run?
- Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
- Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
- Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
- Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.
What people ask before starting
How do you keep a basement dry?
With a designed waterproofing system, usually a cavity drain membrane draining to a pump, sometimes combined with tanking.
Will my neighbours be affected?
New basements usually need party wall agreements. We handle the notices and surveyors.
How do I get a price for basement and cellar conversions in Cardiff?
Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.
Basement and cellar conversions in nearby towns
- Basement and cellar conversions in Whitchurch
- Basement and cellar conversions in Penarth
- Basement and cellar conversions in Caerphilly
- Basement and cellar conversions in Barry
Learn more about basement and cellar conversions, or see every project we cover in Cardiff.