Having the Beams team on hand to manage the project and provide extra reassurance on build decisions was incredibly helpful and made the whole experience stress free.
Kerry
London
They have been extremely efficient and reassuring. It was a complex project but they took it all in their stride. They recommended very good contractors who were all punctual, polite and capable.
Andrew
London
All about trust. I felt comfortable with my money, my project, and my home knowing that the outcome would be to my satisfaction or would be made good.
Chris
London
Orpington's basement conversion experts
Basement work is unforgiving of mistakes. Our vetted Orpington builders specialise in cellar conversions, basement lowering and new-build excavations, working to proper structural and waterproofing standards, with a fixed-price contract agreed before any digging starts.
Cellar conversion, basement conversion or new basement?
Cellar conversion: Converting an existing cellar into usable living space.
Basement lowering: Digging down to increase headroom in an existing basement.
New excavation: Building a new basement beneath a home with no existing cellar.
How basements are waterproofed
A basement needs a proper waterproofing design, following BS 8102, using tanking, cavity drain membranes or a combination of methods suited to the ground conditions and how the space will be used. Getting this specified and installed correctly is what separates a basement that lasts from one that needs remedial work.
What your Orpington basement could become
Extra bedrooms: With natural light wells and proper ventilation.
A home cinema or gym: Fully tanked and insulated for year-round use.
A self-contained annexe: With its own access and services.
Additional living or utility space: Freeing up space upstairs.
What a basement conversion costs in Orpington
Basement costs depend heavily on ground conditions, the extent of excavation and the finish specified. Based on Beams estimates for London basement projects, typical ranges for Orpington homes are set out below, and your builder confirms a fixed price once a structural survey and design are complete.
Basement type | Typical cost range |
|---|---|
Cellar conversion (existing) | £60,000 - £120,000 |
Basement lowering (dig-down) | £150,000 - £250,000 |
New excavation (full basement) | £250,000 - £400,000+ |
How a Beams basement conversion works
1. Free estimate and survey: We assess feasibility and ground conditions.
2. Design and planning: Structural, waterproofing and party wall matters handled.
3. Build to fixed price: A vetted builder delivers the project under contract.
Why a basement conversion is worth it
Where a garden extension or loft conversion is not possible or not enough, a basement adds significant floor area without changing the footprint or roofline of the house, useful on the smaller plots found in parts of Orpington's town centre and surrounding streets.
Converting a basement in Orpington
Ground conditions and the age of a property both affect what a basement project involves in Orpington. Older properties near the town centre and around Chelsfield and Farnborough often have shallow existing cellars that can be lowered, while some newer suburban homes have no basement at all, meaning a full excavation. Party wall agreements apply to semi-detached and terraced houses where work is close to a shared boundary, which is common across much of Orpington's housing stock.
The same design team, vetted builders and fixed-price process sit behind every project. See how our vetted builder network works, from the first design call to final sign-off.
Other services in Orpington
We also help Orpington homeowners with:
Bathroom renovation in Orpington
Kitchen renovation in Orpington
Basement conversion in nearby areas:
Ready to convert your Orpington basement?
Get a free estimate and take the first step. No commitment, no sales pressure.