07450 310772sales@uhmbasements.co.uk FMB  ·  Delta Registered  ·  £10M Insured  ·  25-Year Warranty About Services Areas Our Work Reviews Contact 07450 310772Book a site visit London Basement Specialists · Est. 2009 # Refined basements, quietly engineered beneath London's finest homes. 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. Book a private site visit 07450 310772 30 Years' experience 150+ Basements delivered 25yr Warranty Enquire Now ## Tell us about your project - FMB Accredited - Delta Registered Installers - Considerate Constructors - NVQ Level 6 Directors - Est. 2009 What we build ## Structural basement work, delivered end-to-end. 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. 01 ### Basement Excavation Full underpinning, dig-outs and structural excavation beneath existing London homes. Directly-employed crews, in-house muck-away and concreting. Explore 02 ### Basement Conversion Turn unused sub-floor space into premium living areas, cinema rooms, gyms, guest suites, kitchens. Design-through-build delivery. Explore 03 ### Waterproofing & Tanking Delta Registered Installers. Type C cavity drainage with Delta membrane, sump & pump systems, and 25-year waterproofing warranty. Explore ### Supporting specialisms Basement UnderpinningCellar ConversionDamp ProofingSump & Pump SystemsBasement ExtensionLight Well Installation Why UHM Basements ## A specialist firm, run by the people digging the hole. 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. - One accountable team 25 directly-employed professionals. Same team, start to finish. - Director on site daily Ghedeon attends every site every day. Real accountability. - 25-year warranty Structural + waterproofing warranties on every completed basement. - Delta Registered Delta Registered Installers, FMB members, Considerate Constructors. More about UHM In their own words ## See what our clients have to say about UHM. A slideshow of reviews from London homeowners we have built for, in their own words. Recent projects ## Real basements. Real London homes. View all case studies Completed Battersea · SW8 Tennyson Street 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. Build value£800,000 Jan 2022 → Dec 202324 months Sold for£1.125M In progress Southfields · SW18 Sutherland Grove 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. Build value£725,000 ProgrammeFeb 25 → Jan 26 Live projectIn progress Where we work ## London basements , South London first. 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. - London - Wandsworth - Clapham - Wimbledon - Putney - Balham - Chelsea - Kensington - Richmond upon Thames Kind words ## Repeat clients. Architect referrals. " 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.Federico Santilli Repeat client " 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.Simon Wolanski Basement conversion " 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.Jonathan Chattaway Director, AtelierWest Architects Read all reviews How we work ## Four steps. No surprises. From your first phone call to your 25-year warranty certificate, one team, one point of accountability, one fixed programme. - 01 ### Free site visit A director attends your home, assesses the property and discusses your brief in detail. No obligation, no charge. - 02 ### Detailed written quote Fixed specification, transparent scope, clear payment schedule. You know exactly what you're getting before we lift a shovel. - 03 ### Directly-employed build Our 25-strong in-house team runs your project end-to-end, with a director on site every day. - 04 ### 25-year warranty Structural warranty and Delta-backed waterproofing warranty on completion. Building control sign-off included. Common questions ## Answers before you pick up the phone. Straight answers to the questions we hear on almost every free site visit. Something not here? Ask us directly. 07450 310772Message us ### How long does a London basement excavation take? 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. ### What warranties do you provide? 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. ### Is the quote free? 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. ### Which parts of London do you cover? 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. ### What accreditations do you hold? 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. Book your free site visit ## Ready to dig? Let's talk your London basement through. A director will visit your home, review your plans, and give you a written quote, for free. No obligation. No pressure. - Free site visit - Free written quote - 25-year warranty - £10M insuranceRequest your free quote 07450 310772 Underhouse Management Ltd, London's structural basement specialists. A directly-employed team of 25, delivering meticulous below-ground work across the capital's finest addresses. Established 2009. FMB·Delta Registered·Considerate Constructors ### Services - Basement Excavation - Basement Conversion - Waterproofing & Tanking - Underpinning - Cellar Conversion - Basement Extension ### Areas Served - London - Wandsworth - Clapham - Wimbledon - Putney - Balham - Chelsea - Kensington - Richmond upon Thames ### Contact - 07450 310772 - sales@uhmbasements.co.uk - Unit C220A, Trident Business Centre,89 Bickersteth Rd, London SW17 9SHBook a site visit © 2026 Underhouse Management Ltd (t/a UHM Basements). Company No. 06968521. Privacy Policy·Terms & Conditions·Cookie Policy·25-year warranty · £10M insurance Call nowBook a site visit