Our Specialisms
Basement Waterproofing
London
Cementitious and membrane tanking systems — trusted by London specialists for cellar tanking and damp proofing — to keep basements and below-ground conversions dry, protected, and ready for finishing.
What is Tanking?
Tanking is a waterproofing method applied to walls and floors below ground level to prevent water ingress into habitable or storage space. As specialist basement waterproofing installers, we also handle cellar tanking and damp proofing for older properties across London.
The two main approaches are cementitious slurry tanking, a barrier system bonded directly to masonry, and cavity drain membrane systems (such as Newton, Delta, or Sika), which manage water pressure by channelling it to a sump rather than blocking it outright.
With basement conversions increasingly common across London's higher-value properties, correctly specified tanking has become essential groundwork before any finishing plaster or decoration is applied below ground.
Why It Matters
- Prevents damp and water damage to below-ground living or storage space
- Often required for basement conversions to meet building control sign-off
- Barrier tanking and cavity drain membrane systems suit different water pressure conditions
- Protects finishes such as polished plaster, microcement, and traditional plaster applied above it
- Specialist detailing is required at junctions, pipe penetrations, and floor-to-wall joints
- Essential for basement digs and lower-ground-floor conversions across London
Our Tanking Process
Every tanking project starts with an honest assessment of water ingress and pressure conditions — the wrong system for the conditions is the most common cause of failure.
Survey & Assessment
On-site survey of water ingress patterns, ground conditions, and existing structure.
System Specification
Selection between cementitious barrier tanking and cavity drain membrane systems, based on conditions.
Tanking Installation
Installation of the chosen system, with careful detailing at joints, corners, and penetrations.
Sump Integration & Testing
Sump and pump integration where required, followed by testing before finishes are applied.
Basement Waterproofing for London Conversions
Tanking is often referred to more broadly as basement waterproofing, and it's a critical stage in any below-ground conversion. Getting the waterproofing specification right at design stage — not after water ingress appears — is what protects the finishes and fit-out that follow.
We work to BS 8102, the British Standard for protecting below-ground structures from water, and can advise on the appropriate waterproofing grade for the intended use of the space, from storage areas through to fully habitable basement rooms.
Our tanking and basement waterproofing work is frequently specified alongside structural waterproofing engineers and building control on larger basement dig and conversion projects, ensuring the finished space meets sign-off requirements before any plaster, microcement, or decorative finish is applied.
Frequently Asked Questions
Answers to common questions we hear from clients, architects, and designers.
Cost depends on the tanking system chosen (cementitious slurry vs. cavity drain membrane), the basement's size, and the extent of any sump and pump installation required. We quote after an on-site survey of water ingress patterns and ground conditions, since the wrong system for the conditions is the most common — and costliest — mistake.
Related Specialisms
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Discuss Your Project
Planning a basement conversion or dealing with damp below ground? Talk to us early in the project.
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