Basement
conversions
in Putney, SW15
Architects, Engineers, Surveyors & Builders Under One Roof.
Surveyor-led refurbishment advice via Hampstead Chartered Surveyors →One Studio. One Contract. One Team.
We design and build Putney basement conversions with basement excavation, cellar conversion, and underpinning for properties on Putney Hill, Putney High Street, Lower Richmond Road - structural engineering, party wall coordination, underpinning, waterproofing, drainage pumps, lightwells and full interior fit-out for period homes, townhouses and prime London properties where ground conditions, neighbour risk and sequencing need handling properly.
Basement Conversions in Putney: What You Need to Know
Every basement conversion project in Putney is designed to respect the Putney Conservation Area and the character of Victorian villas, Edwardian terraces, riverside mansion blocks. Our in-house RIBA Chartered Architects handle Wandsworth planning applications, our chartered structural engineers specify any load-bearing work, and our directly-employed trades deliver the build under one fixed-price contract. We coordinate Building Control, Party Wall awards where needed, and all certifications through to handover.
Putney has conservation area coverage in parts, so some properties will need planning permission for external changes while others may proceed under permitted development. We assess each property individually.
Our basement conversion projects in Putney are delivered by our in-house team of RIBA architects, structural engineers and specialist tradespeople. Every project is managed under a single fixed-price contract with no hidden costs.
Putney stretches from the river up towards the heath, within the London Borough of Wandsworth, and its best streets carry conservation protection that the borough backs with Article 4 controls. A basement on Putney Hill — home to grand Victorian villas and mansion blocks — is treated first and foremost as controlled structural work, assessed against that position before excavation method is settled.
The engineering follows the ground rather than the postcode. Costs on a Putney basement depend on whether the house is a villa or a terrace, on party-wall agreements with the neighbours either side, on drainage and rear levels, and on the tree and boundary constraints common along the established streets running down to the river. Putney Hill's villas differ from the Edwardian terraces off Disraeli Road and the Lower Richmond Road in exactly the ways that decide whether a scheme converts an existing cellar or digs a new one.
Those two routes carry very different price tags. Converting cellar space that already exists is priced, London-wide, at £750–£3,000 per square metre of the converted area, and a fully finished result can exceed £6,000/m²; a fresh excavation with underpinning runs £2,100–£4,000 per square metre of excavated area, with full fit-out counted separately again. We test a Putney Hill or riverside scheme against both figures before recommending either.
Basement Conversions in Putney: Applied to the Local Stock
Putney sits in the London Borough of Wandsworth, with conservation areas protecting its best streets between the river and the heath. Basement excavation / new basement — London-wide rate guidance: Excavation/underpinning: £2,100–£4,000/m² excavated area, excluding full fit-out (Ideal Home, Sept 2025).
Sources: Wandsworth Council - Conservation area appraisals register (2026); Basement excavation / new basement (Ideal Home basement cost guide, Sept 2025; Camden basement Article 4 Direction, accessed 2026-06) (2026)
What a Basement Conversion Involves
Digging out a basement adds a complete new storey without touching the garden or the street elevation — and it is the most engineering-led work we do. Ground conditions, foundation depths and the water table are investigated before a price is ever fixed, because below-ground surprises are expensive precisely when they are unplanned. Each project moves through four disciplines, delivered by one team under one contract.
- Excavation — the dig itself, planned around access, spoil removal logistics and temporary support of the house above
- Underpinning — foundations deepened in short, engineer-sequenced sections, with movement monitoring on your property and your neighbours’ throughout
- Waterproofing — a tanked, integral or cavity-drain system (Type A, B or C to BS 8102) selected for your site’s ground conditions, not by habit
- Fit-out — insulation, ventilation, light wells, staircase, plaster and finishes brought to the same standard as the floors above
How We Run Your Project
Below-ground work punishes improvisation, so every stage is closed out before the next one starts.
- Ground investigation — bore holes establish soil type, bearing capacity and water table before feasibility is confirmed.
- Design & consents — layout, light wells and stair position from our architects; underpinning sequence from our structural engineers; planning and any Basement Impact Assessment handled for you.
- Fixed-price contract — priced after the soil investigation, so ground conditions are our risk rather than your variation.
- Excavation & underpinning — sequenced digs and pours with live structural monitoring, never more than the engineer’s design allows at once.
- Waterproofing & shell — membrane or structural system installed and inspected before anything conceals it, with sump and pump provision where the site needs it.
- Fit-out & handover — services, finishes, building control sign-off and a certification pack at completion.
On site, expect 12–16 weeks for a cellar conversion and 16–24 weeks for a full dig-down — the curing time between underpinning sections cannot safely be compressed. Read the full basement conversion guide for waterproofing systems, ceiling heights and light-well design in depth.
The regulatory load is real: a chartered structural engineer must design and certify the underpinning methodology, and most excavations within three metres of a neighbouring building engage the Party Wall etc. Act 1996 — notices, schedules of condition and often a formal award before work can start. Many boroughs add a Basement Impact Assessment covering hydrology and construction management. Our planning guide library sets out what applies where.
Why Hampstead Renovations
Basements fail when design, engineering and waterproofing are handled by separate firms working from different assumptions. Here they sit under one roof: in-house RIBA Chartered Architects shape the space, our own structural engineers design and supervise the underpinning, and RICS surveying support through our sister company covers party wall and condition matters. Every project carries £10M public liability cover, a genuinely fixed price agreed after ground investigation, and a 10-year structural and waterproofing warranty. Send an enquiry before 2pm on a weekday and you will hear back from us that same day.
Basement Conversions in Putney: Questions
Is basement work in Putney controlled by conservation rules?
Yes. Putney's position in the London Borough of Wandsworth, between the river and the heath, comes with conservation areas protecting its best streets, and Wandsworth adds Article 4 controls with close scrutiny of external change on top — so a Putney basement is assessed as controlled structural work before anything else.
What structural and party-wall work does a basement on Putney Hill involve?
Substantially. A Putney Hill basement's cost depends on whether the house is villa or terrace in structure, on party-wall agreements with neighbours on both sides, on drainage and rear ground levels, and on tree and boundary constraints along the established street — all before glazing or access into the garden is even discussed.
Which Putney streets suit a basement conversion?
It depends on the street. Putney Hill carries grand Victorian villas and mansion blocks well suited to a full new dig, while Disraeli Road and the streets off the Lower Richmond Road bring long Edwardian and Victorian terraces where converting whatever cellar already exists is often the more natural Putney basement route.
How much does converting an existing cellar cost in Putney?
Putney houses that already have cellar space benefit from the cheaper of the two basement routes: converting it into finished rooms runs £750–£3,000 per square metre of converted area, London-wide, with a fully finished result able to exceed £6,000/m² — because the digging, in effect, has already been done.
What does a new basement excavation cost in Putney?
A new basement dug from scratch in Putney, complete with underpinning, is priced at £2,100–£4,000 per square metre of excavated area, before the full fit-out is added on top. On Putney Hill's larger villa plots, that is often the figure a scheme is measured against.
More Services in Putney
Book a Free Consultation
Visit our studio or invite us to survey your home. We’ll assess scope, discuss design possibilities and provide an honest budget framework — completely free.
Free Consultation
We survey your property, discuss your vision and provide a clear budget framework.