Basement and cellar conversions in Whitchurch, South Glamorgan

Covering Whitchurch, South Glamorgan

Whitchurch, South Glamorgan is about 3 miles north-west of Cardiff. We also cover Cardiff (3 miles to the south-east), Caerphilly and Penarth.

Homes in South Glamorgan

Welsh homes include long terraces built into hillsides, stone cottages and modern estates, and sloping sites often shape how and where an extension can go.

What goes into a basement conversion?

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.

Lightwells and windows for daylight and escape
Ventilation, heating and electrics
Finished floors, walls and ceilings

How much should I budget for a basement conversion?

Use these ranges to budget for basement and cellar conversions; the survey turns them into a fixed price for the agreed specification.

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

Do you need permission for a basement conversion in Whitchurch, South Glamorgan?

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 can affect a basement conversion?

Groundwater levels drive the waterproofing design and cost.
A pump for the drainage system needs a battery back-up.

What are the steps?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
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.

Basement and cellar conversions: common questions

How much does a basement conversion cost?

Converting an existing cellar costs about £1,900 to £3,000 per square metre including VAT. A new excavated basement is around £4,200 to £6,600 per square metre.

How long does it take?

About 6 to 12 weeks for a cellar conversion and 16 to 30 weeks for a new basement.

Can you visit a house in Whitchurch, South Glamorgan to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Basement and cellar conversions in nearby towns

Learn more about basement and cellar conversions, or see every project we cover in Whitchurch.