We design, excavate and waterproof basement conversions for homeowners across South London, delivered start to finish by our own in-house team of 25. 150+ basements completed since 2009, backed by a 25-year structural and waterproofing warranty and £10m insurance. Free site visit with a director in attendance.
We're not a generalist builder that also digs basements. Every director, every operative, every piece of equipment we use is set up for structural work below the water table in tight London terraces.
01Full underpinning, dig-outs and structural excavation beneath existing London homes. Directly-employed crews, in-house muck-away and concreting.
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02Turn unused sub-floor space into premium living areas, cinema rooms, gyms, guest suites, kitchens. Design-through-build delivery.
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03Delta Registered Installers. Type C cavity drainage with Delta membrane, sump & pump systems, and 25-year waterproofing warranty.
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Founded by Ghedeon Costin in 2009 and now co-directed with Daniel Purdy, UHM has been a South London basement specialist for over a decade. We're built around a directly-employed team of 25, so quality, programme and safety stay in our hands from first survey to final handover.
25 directly-employed professionals. Same team, start to finish.
Ghedeon attends every site every day. Real accountability.
Structural + waterproofing warranties on every completed basement.
Delta Registered Installers, FMB members, Considerate Constructors.
A slideshow of reviews from London homeowners we have built for, in their own words.
Three-bedroom detached new-build with lower-ground floor. Open-plan kitchen, dining and living space with bi-fold doors onto a private patio. Two double bedrooms and family bathroom on raised ground floor; principal suite with en-suite on the first floor.
Three-bedroom detached new-build with full-size basement. Close to Southfields Underground (District Line). Designed for modern family living with flexible spaces and high-quality finishes.
Our workshop is in Tooting. Most of our projects sit within 20 minutes of SW17: fast site visits, quick response on live works and genuine local knowledge of party walls and London clay.
We have used UHM Basements on two occasions. On both occasions the work was carried out and finished perfectly and professionally. We have not had a single issue since completion. The owners are honest and straightforward to deal with, they know exactly what they are doing.
UHM completed a fantastic conversion of our basement to a bedroom and en-suite. Ghedeon and his team worked efficiently to the schedule. Communication was clear. Great quality, good value, and the work passed building control inspections.
We have worked with Ghedeon and Dan at UHM on a number of projects over the past 8 years. Their 'can-do' attitude is a real asset when running large projects in Central London. We regularly recommend UHM to anyone requiring a professional basement contractor.
From your first phone call to your 25-year warranty certificate, one team, one point of accountability, one fixed programme.
A director attends your home, assesses the property and discusses your brief in detail. No obligation, no charge.
Fixed specification, transparent scope, clear payment schedule. You know exactly what you're getting before we lift a shovel.
Our 25-strong in-house team runs your project end-to-end, with a director on site every day.
Structural warranty and Delta-backed waterproofing warranty on completion. Building control sign-off included.
Straight answers to the questions we hear on almost every free site visit. Something not here? Ask us directly.
Most residential basement excavation and conversion projects in London run between 9 and 14 months from break-ground to handover, depending on depth, party wall complexity and finish specification. We give a realistic programme in the written quote and hold to it, Simon Wolanski's testimonial above is a fair example of how we manage schedule and communication.
Every UHM basement is delivered with a 25-year structural warranty and a 25-year waterproofing warranty (as Delta Registered Installers). We also carry £10,000,000 all-risks insurance covering both public liability and employers' liability.
Yes. Site visits and written quotes are always free: there's no fee for us to visit, survey and price your project. We only ask that you're the property decision-maker and that a basement or below-ground project is genuinely on the table.
We're a London-only specialist, primarily working across South London: Wandsworth, Clapham, Wimbledon, Putney, Balham: with regular projects in Chelsea, Kensington and Richmond upon Thames. Our workshop is in Tooting (SW17), so response times for site visits are quick across the capital.
UHM is an accredited FMB member (Federation of Master Builders), a Delta Registered Waterproofing Installer and a member of the Considerate Constructors Scheme. Both directors hold NVQ Level 6 Site Management qualifications, and the wider team carries SSSTS, SMSTS, Asbestos Awareness, Confined Space, First Aid, Temporary Works Co-ordinator and Face Fit training.
A director will visit your home, review your plans, and give you a written quote, for free. No obligation. No pressure.
