Wykamol CM20 Geotextile Waterproofing Membrane
If you’re dealing with high water volume against a structure, you need two things: a dependable waterproofing strategy and a drainage layer that keeps water moving to a discharge point. Wykamol CM20 Geotextile Waterproofing Membrane is designed for that job, a 20mm studded HDPE membrane with a thermally bonded geotextile backing that filters fines while maintaining a clear drainage void.
Used correctly as part of a complete waterproofing design, CM20 helps isolate and protect structures from surrounding ground and relieve hydrostatic pressure from the face of the structure.
Where Wykamol CM20 Geotextile Waterproofing Membrane Is Used
CM20 Geotextile Waterproofing Membrane is assessed/positioned for use on:
- Walls below ground level and floors (new build or existing buildings)
- As a protection and drainage board in conjunction with horizontal/vertical external waterproofing systems
- Typical structural drainage applications such as retaining walls, podium decks, external tanking and green roof builds
How Wykamol CM20 Geotextile Waterproofing Membrane Works
The studded core forms a drainage space. Water passes through the geotextile into the void and is directed to a discharge point, while the geotextile helps stop soil/debris migrating into the drainage channels. Wykamol also notes the bonded geotextile helps prevent deformation into the void under backfill loads, supporting long-term drainage continuity.
Technical Specification
| Stud Height | 20mm |
| Membrane Thickness | 1.0mm |
| Total Depth | 21.5mm |
| Weight Per Unit Area | 1000 g/m² |
| Air Gap Volume | 14.6 l/m² |
| Roll Size | 2.0m × 10m |
| Water Tightness | Pass at 60 kPa for 24h (EN 1928) |
| Compressive Strength | 180 kN/m² |
Wykamol CM20 Geotextile Waterproofing Membrane Installation
CM20 can be installed vertically or horizontally, with the geotextile facing outwards, and must run down to (or just below) the level of the drainage provision, depending on your design.
For sealed installations, the BBA certificate notes that joints and fixings must be sealed using compatible sealing methods (e.g., butyl tapes/ropes or sealed plugs) and that drainage channels/gullies or sumps/pumps should be installed as needed to manage water.
Wykamol’s datasheet also references sealing overlaps with their tapes and ensuring drainage channels are appropriately positioned and surrounded by granular infill.
Compliance & Certification
- BBA Agrément Certificate 18/5595 covers the stated damp-proofing/drainage/protection uses in the UK.
- Declared as Type V waterproofing sheet to BS EN 13967:2012 + A1:2017 (DoC/DoP).
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