Basement specialistsacross London ,one team, every borough.
UHM Basements has delivered over 150 basements across London since 2009: Victorian terraces in Wandsworth, Edwardian houses in Wimbledon, Georgian townhouses in Chelsea and Kensington, and riverside properties in Putney and Richmond. One 25-strong directly-employed team and 25-year warranties as standard.
Our own 25-strong team · Free site visit and quote · 25-year warranty.
London is our only market, and it shows in how we work.
London basements are unlike anything else in the UK. Compact urban plots, party walls a brick thick, clay subsoils, high water tables near the Thames, listed façades in Chelsea and Kensington, restricted access streets in Clapham and Balham, and boroughs each with their own planning stance. We've spent 17 years learning how to deliver premium basements inside those constraints, and we work nowhere else.
All London postcodes inside the M25. Deepest coverage in South & West London: Wandsworth, Clapham, Wimbledon, Putney, Balham, Chelsea, Kensington and Richmond upon Thames, where our directly-employed teams are on projects daily.
Call or email and a director will get back to you to arrange a free site visit at a time that suits you.
Victorian and Edwardian terraces, semi-detached and mansion blocks, Georgian townhouses, 1930s semis, converted mews, listed buildings and modern infill houses. We've worked on every London stock.
Full excavations for family kitchen-diners, cellar conversions to habitable rooms, Type C cavity drainage for basements that already flood, underpinning to enable lower-ground floors, and light wells to bring daylight into deep London plans.
Every basement discipline, under one roof.
Every basement discipline UHM offers is available across London, from a two-week cellar tank-out to a twelve-month full-house excavation and conversion. Each service page below explains the technical detail, warranties and what's included.
Basement Excavation
New-build basements dug and structurally formed beneath your existing London home, sequenced underpinning, engineered retention.
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Basement Conversion
Turn an excavated basement into a fully habitable London floor, kitchens, cinemas, guest suites, matched ceiling heights.
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Waterproofing & Tanking
BS 8102 compliant Type C cavity drainage and tanking, Delta Registered Installers, 25-year insurance-backed warranty.
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Underpinning
Structural underpinning to lower ground floors and stabilise London terraces, Temporary Works Coordinator on every job.
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Cellar Conversion
Convert existing London cellars into dry, habitable rooms, no dig, minimal disruption, fully warranted.
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Damp Proofing
Diagnostic damp surveys and targeted damp-proofing across London properties, no scattergun tanking, no upsells.
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Sump & Pump Systems
Twin-pump, alarmed sump systems installed and commissioned, the mechanical backbone of every reliable London basement.
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Basement Extension
Extend downwards where extending outward isn't possible: full planning, party wall and design-build service.
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Light Well Installation
Bring daylight into deep London basements with engineered light wells: glazing, drainage and safety detailing included.
Learn moreWhy London homeowners choose UHM.
Basements are the highest-risk building work most Londoners will ever commission. Our answer to that risk is depth of coverage: one directly-employed team, one company insurance-backed, one warranty document at the end.
One accountable team, start to finish
Since 2009, across every South & West London postcode you'll find in our footer | plus jobs in North and East London on referral. Every project on our books is delivered by the UHM team.
25 directly-employed staff
Excavators, underpinners, Delta Registered waterproofers, carpenters, electricians and plasterers | all on our payroll. Nobody arrives to your London home whose name we don't know.
25-year warranties as standard
Structural and waterproofing warranties both run to 25 years, insurance-backed by £10M public liability cover | the same document across every London borough we serve.
The specific problems London basements face.
London basements fail in predictable ways. Once you've dug 150+ of them, the patterns are obvious, and every UHM design starts by engineering them out from day one.
London clay & shrink-swell movement
Much of London sits on London Clay | a shrink-swell soil that heaves and settles seasonally. Basements dug into it need engineered underpinning sequences, not opportunistic digs, or you get cracked structures and heave-lifted floors within two winters.
High water tables near the Thames
Anywhere close to the Thames, its tributaries or historic river routes runs a high water table. Hydrostatic pressure attacks concrete substrates continuously. Every UHM design is Type C cavity drainage first, tanking second | never the other way round.
Party walls & narrow terraces
Most London homes share at least one party wall. Notifiable works under the Party Wall etc. Act 1996 apply almost every time. We handle Party Wall notices, awards and adjoining-owner liaison as part of the standard scope, not a bolt-on.
Restricted access & conservation controls
Chelsea, Kensington and Richmond bring conservation area consent, listed building consent and Article 4 restrictions. West London mews and Clapham back streets bring skip and muck-away logistics. We plan both before pricing.
Structured stages, no shortcuts.
Every UHM project, whether in London or elsewhere in London, runs through the same disciplined sequence. You'll always know what's happening next, who's doing it and when it completes.
- 01
Free site visit
Director-led survey of your London property | measured, photographed, condition-noted. Same visit, no charge.
- 02
Written quote & design
Fixed written quote, structural strategy, Party Wall notes and BS 8102 waterproofing spec | before you commit.
- 03
Consents & permits
We manage Building Control, Party Wall Awards and | where required | planning liaison with your London borough.
- 04
Build on-site
One directly-employed 25-strong team. Weekly reporting, protected neighbours, tidy site.
- 05
Handover & warranty
Building Control sign-off, commissioning, 25-year structural and waterproofing warranties, £10M insurance-backed.
Do you cover every London borough?
Yes. Our directly-employed teams work anywhere inside the M25, with our densest live workload in South & West London: Wandsworth, Clapham, Wimbledon, Putney, Balham, Chelsea, Kensington and Richmond. For central and North London we still operate as a full main contractor.
How fast can you visit a property in London?
Get in touch by phone or email and we will arrange a free, director-led site visit at a time that suits you.
How much does a London basement cost?
Prices vary too much by property, ground, water table and finish for a public price list to be useful. Every enquiry gets a free written quote after a real site visit, no obligations, no follow-up sales calls unless you want them.
Do you handle Party Wall Awards and Building Control in London?
Yes. Party Wall notices, awards, Building Control inspections and, where required, planning and conservation area liaison are managed by UHM as part of the standard scope. You do not need to appoint a separate project manager.
What warranty do London projects come with?
25-year structural warranty and 25-year waterproofing warranty, both insurance-backed by our £10M public liability cover. Warranty documents are issued on final handover after Building Control sign-off.
Which London areas do you have the most experience in?
Wandsworth, Clapham, Wimbledon, Putney and Balham account for the largest share of our 150+ projects. Chelsea, Kensington and Richmond are our most common conservation-controlled areas.
Serving South & West London
Book your London basement site visit.
Free, director-led, and no pressure. If we're not the right fit for your London property we'll say so on the visit. If we are, we'll price it in writing.
- Free site visit
- Free written quote
- 25-year warranty
- £10M insurance
- Directly-employed team