Cavity drain membrane systems, designed and installed to BS 8102.
A full design and installation service using dimpled cavity membranes, collecting and draining ingressing water away from the property — with sump and pump systems where needed.
Bensleys offers a full design and installation service for basement waterproofing using cavity drain membrane systems, following British Standard BS 8102, designated as ‘the protection of structures against water from the ground’.
These are polyurethane plastic sheets with dimples moulded into them, fixed mechanically to the walls to create a cavity between the substrate and the internal wall-plaster finish. This allows any ingressing water to be collected and drained away from the property; if necessary, we can also install sump and pump systems in the floor structure.
If necessary, an insulation-backed plasterboard can be fitted to the cavity drain membrane system to increase the U-value of the wall structure. These works follow Property Care Association guidelines, with the system designed by Bensleys’ own qualified surveyors.
Guarantee & Insurance
These systems are covered by Bensleys' standard guarantees, which can be underwritten by Guarantee Protection Insurance Ltd or the Triton User Group as required — giving you an insurance-backed guarantee, not just our word.
How it works
Dimpled cavity
Moulded dimples create a cavity between the substrate and the finish, giving water somewhere to go instead of pushing through.
Drainage
Sump & pump if needed
Where the water table or ingress rate requires it, a sump and pump system is installed in the floor structure to manage the flow actively.
Thermal performance
Insulation-backed option
An insulation-backed plasterboard can be added to increase the U-value of the wall, useful where the basement will be a habitable space.
How we install it
From design to a guaranteed, dry basement.
Survey & design
Our qualified surveyors assess the structure, water pressure and intended use of the space, and design the system to BS 8102.
Membrane installation
The dimpled membrane is mechanically fixed to the substrate, creating the drainage cavity across the treated area.
Drainage & sump/pump
Where needed, a sump and pump system is installed in the floor structure to manage collected water actively.
Finish & guarantee
Plaster or insulation-backed plasterboard is fitted, and the completed system is covered by our insurance-backed guarantee.
Related systems
Other basement waterproofing options
Each has its place, and the right choice depends on wall construction, water pressure, and whether the space needs a sump and pump. Each system below has its own dedicated page.
Cementitious Tanking Membranes
A modified cement slurry or multi-coat render applied directly to the internal face, stopping moisture at the point of entry…
Find out moreExternal Ground Damp Proof Membrane
Installed with suitable drainage to the perimeter of new-build basements, or where ground levels are lowered around an existing one…
Find out moreFrequently Asked Questions
Find clear answers for Cavity Drain Membranes.
What is a cavity drain membrane?
What standard does this system follow?
Can insulation be added to a cavity drain membrane system?
Is the guarantee on cavity drain membranes insured?
Considering a cavity drain membrane? Let's design it properly.
Our qualified surveyors will confirm it's the right system for your structure before anything is specified.