BS 8102 · Type A / B / C · London & Surrey
Structural waterproofing and basement conversions, run by one family. We stop the water first, design it to BS 8102, then finish the space down to the last coat of paint.
Structural waterproofing
Groundwater is seasonal. A cellar that is bone dry in August can take water in February, and a specification written around the dry visit fails the first wet winter. Every design we produce is built around the worst case the ground can present, not the day we happened to see it.
Type A
A continuous waterproof barrier applied to the structure — cementitious slurries and spray applied membranes. The right answer where the structure is sound and the water head is properly understood.
Wykamol HydraFlex · hand & spray applied
Type B
The structure is the waterproofing. Water-resistant concrete with every joint, construction detail and service penetration designed and sealed as part of the structure itself.
HydraDry mortar · new build & underpinned structures
Type C
Cavity drain membrane, perimeter drainage channel and a managed discharge. Rather than resisting water, it collects and removes it — and stays maintainable for the life of the building.
Wykamol Waterguard · Grade 3 habitable
Membrane
Studded HDPE membrane to walls, floors and soffits, sealed and fixed to detail. The quality of a Type C system lives in the junctions, the corners and the service penetrations.
Wykamol CM3 / CM8 / CM20 · BBA certified
Tanking
Fast, seamless and uniform across complex geometry, with none of the lap joints that hand application leaves behind. Ideal for vaulted cellars and irregular Victorian substructures.
Peristaltic pump · no lap joints
Pumped discharge
Twin pumps, battery backup and a high-level alarm, sized to the calculated inflow. A drained system is only as good as the pump that empties it, so we specify for failure as well as function.
Wykamol SumpFlo 301 / 303
Technical datasheets, BBA certificates and the full drawings manual →
How we work
The same people who diagnose the water problem hand you back the finished room. Nothing is subcontracted across the join, because that join is exactly where waterproofing projects go wrong.
We establish where the water is actually coming from — groundwater, lateral seepage, a failed historic tanking system or plain condensation. They look alike on the wall and need entirely different answers.
A written waterproofing design against the intended grade of use, produced by a CSSW-qualified surveyor. You get the drawing and the reasoning, not just a price.
Structural works, then the waterproofing system itself, installed by our own teams and checked at every stage before anything is covered up and made invisible.
Floors, walls, lighting, heating, joinery and decoration. This is the part most waterproofing firms hand over to somebody else — we carry it through to the final coat.
Commissioning, a maintenance schedule for the drained elements, your guarantee documentation and the option of an insurance-backed guarantee on the completed works.
Basement conversions
Your home's potential shouldn't end at the ground floor. A dry, warm, properly lit basement is the cheapest square metreage you will ever add to a London property — provided the water was dealt with first.
Below ground is acoustically ideal: no neighbours, no street noise and mass on every side. Isolation and ventilation designed in from the start.
Stable, cool and naturally dark. The thermal mass that makes a cellar hard to heat is exactly what makes it right for storage.
High-moisture rooms below ground demand serious ventilation and vapour control. We plan both alongside the waterproofing, never after it.
Kitchens, playrooms, offices and self-contained annexes — habitable Grade 3 space, finished to the same standard as the floors above.
Family run
Crystal Waterproofing Renovations is a family business built on trust, integrity and decades of hands-on work below ground. We manage every stage ourselves, from heavy structural waterproofing through to the final whole-home conversion finishes, with clear communication and no handovers between trades that don't talk to each other.
Because a genuinely exceptional room starts beneath the surface, every project is grounded in precision engineering and high-grade damp-proofing before a single aesthetic detail is added. That order never changes, and it is the whole reason our work lasts.
We work from South Croydon across London and the Surrey belt — close enough to the properties we look after that we can get back to them when it matters.
We don't just stop water. We create dry, distinguished spaces for your family to enjoy for generations.
Where we work
The right specification changes with the ground, and the ground changes fast around London — clay in the centre, gravels along the river, Chalk on the Downs. Each region below has its own notes.
Request a quote
Describe what you're seeing and we'll tell you honestly whether it needs a full waterproofing system or something far simpler. Surveys across London and Surrey.