Delta Registered Installers, Type C cavity drainage systems, twin sump-and-pump commissioning and a 25-year waterproofing warranty, installed by the same directly-employed team that dug your basement.
Delta Registered Installers · 25-year waterproofing warranty · Free site visit and written specification.
A London basement below ground level is permanently trying to let water in. Waterproofing is the engineered system: membrane, drainage, pumps and detailing, that keeps the finished floor dry for decades, not months. Get it right once and it disappears. Get it wrong and every finish above it becomes disposable.
The design and installation of a below-ground waterproofing system to BS 8102, Type A (barrier), Type B (structurally integral) and/or Type C (cavity drainage): including Delta membranes, drainage channels, twin sump-and-pump systems and full commissioning documentation.
Homeowners with a new basement excavation, an existing basement showing signs of damp, a converted cellar that has failed, or a completed basement being sold where the buyer's surveyor has flagged waterproofing evidence.
During new excavation (designed in from day one), as a retrofit to a damp or failing basement, or before sale where warranty documentation is missing.
Waterproofing is the discipline that turns a basement into a habitable, valued and insurable floor. It's the single most-audited element by buyers' surveyors, and the most common cause of six-figure remedial jobs.
Every UHM project runs through the same structured stages. You'll always know what's happening next, who's doing it and when it completes.
A director surveys the basement, tests moisture readings, and identifies the water-management issue: new build, retrofit or failing system.
Type A, B, C or hybrid system selected to match the risk classification and end use. Documented design, drawings and specification issued.
Delta membrane system installed by Delta Registered Installers, drainage channels chased in, sump chambers set to correct falls.
Twin sump-and-pump systems installed with alarm and battery back-up, tested against flow rates, and documented.
25-year waterproofing warranty issued, commissioning report and maintenance schedule handed over in writing.
BS 8102 recognises three types of below-ground waterproofing. Each has a place, and mature specification usually combines them. Here's how we approach each.
A physical barrier applied to the structure that prevents water ingress. Cementitious tanking, bituminous coatings and specialist slurries. Effective when the substrate is sound and the risk class is right, but a bonded barrier is vulnerable to structural movement.
The structure itself resists water, waterproof concrete with engineered joint detail. Used on new-build basement rafts and walls where the RC design is specified for waterproofness.
A drained cavity behind an internal membrane collects any water that reaches the structure and channels it to a sump-and-pump system. The most reliable, maintainable choice for occupied residential basements because it accepts water rather than fighting it.
Where a basement is already failing, we survey moisture readings, identify the failure mode and design a retrofit, usually a Type C cavity drainage system introduced with minimum disruption to finished rooms. Structural rectification, if needed, is scoped separately.
Delta-backed warranty, only available because we're Delta Registered Installers with the training to install and commission the full system.
Every UHM waterproofing system is designed to the recognised British Standard, not to a product datasheet.
The team who waterproofs is the team who dug the hole and will finish the conversion. No blame gaps between structural, waterproofing and fit-out.
For failing basements, our directly-employed crew can start the diagnostic and design stage quickly, most surveys booked within days.
Commissioning reports, warranty certificates and manufacturer documentation, the paperwork a buyer's surveyor actually asks for.
A properly designed waterproofing system does its job in silence for the life of the building. That's the point.
The typical failing London basement isn't a flood, it's a slow, quiet failure that becomes visible on a Sunday afternoon in November. Damp on a party wall. A faint musty note. Salts on the plaster. By then the fix isn't a can of paint.
Once moisture is behind plasterboard, joinery and floor build-ups, every finish that touches it is condemned. Skirtings, wardrobes, floors and plaster all become strip-out jobs.
Sustained damp in a habitable basement means airborne mould spores and elevated humidity. It affects the way rooms smell, feel and are used, and it isn't a cosmetic problem.
Buyers' surveyors specifically look for waterproofing evidence in London basements. Missing warranties, unbranded membranes and undocumented pumps trigger retention or renegotiation.
Assuming one bucket of tanking slurry counts as waterproofing.
Installing cavity drainage without a properly designed sump and pump.
Fitting a single pump with no back-up and no alarm.
Using non-registered installers, the warranty is only as good as the installer's status.
Painting bituminous coatings over damp brickwork and calling it 'tanked'.
Skipping the commissioning report and maintenance schedule at handover.
Straight answers we give on almost every free site visit, cost, timeline, guarantees and what's included.
Tanking (Type A) is one specific approach, a bonded barrier applied to the structure. Waterproofing is the broader engineering discipline including Type A, Type B (structurally integral) and Type C (cavity drainage), designed together to BS 8102. Most habitable London basements are best served by cavity drainage or a hybrid.
Priced per project. Cost depends on the size of the basement, the system specified, whether it's new-build or retrofit and the state of the existing structure. Site visits and written specifications are free.
As part of a new-build basement, waterproofing is installed within the main programme. As a standalone retrofit, most residential systems complete in three to six weeks depending on size and access.
25 years, as Delta Registered Installers. The warranty is documented and provided at handover, a piece of paper your solicitor and future buyer will want to see.
Yes, for habitable basements we install a twin pump system with automatic failover, battery back-up in mains power failure, and an audible alarm. A single pump is a single point of failure, we don't specify them for occupied basements.
Yes, annual servicing is recommended and included in our maintenance schedule. Pumps, floats and alarms should be checked yearly, and battery back-ups tested and replaced on cycle.
Yes. Retrofit Type C cavity drainage can be installed into a completed basement with careful sequencing to minimise disruption to finished rooms. We survey first and issue a written specification before any work.
Delta Registered Installers' 25-year waterproofing warranties, together with UHM's £10M all-risks insurance, are recognised documentation for lenders, insurers and buyer's surveyors.
A director will visit, survey the basement and issue a written waterproofing specification, for free. If retrofit isn't the right answer, we'll tell you.
