Waterproofing systems: Cavity Drain Membranes (Type C)
Type C waterproofing is defined in BS 8102: 2009 as ‘drained protection’ which is achieved by the incorporation of a drained cavity within the basement structure. The basement wall must provide enough primary resistance to water ingress to ensure the cavity only accepts a controlled amount of water or dampness. Water is collected in the cavity between the external wall and an internal lining (cavity drain membrane) and diverted to a suitable drainage point.
The use of cavity drain membranes does not allow pressure to build up against the internal construction and the air gap allows the structure to breathe - and to some extent to dry out. Cavity drain membranes are loose laid on floors and fixed to walls using special plugs and sealing materials, with little or no preparation required to the substrate. Once the membrane has been fitted, wall surfaces can be dry lined or plastered directly and floors can be screeded or a floating dry board system installed.
A BBA certified high-density polyethylene (HDPE) cavity drain membrane which is impermeable and resistant to the usual chemicals in the building construction. Tough but pliable and can be bent round corners and projections without risk of breaking even in very low temperatures. The product can be easily cut with a knife or scissors. Available in rolls of 2.07m x 20m.
BBA certified Platon P20 is a heavy duty, deep studded HDPE cavity drain membrane principally used on floors and ideal for areas subject to high volume water penetration. Platon P20 is impermeable to water, gas and water vapour. The deep stud profile is designed to resist blockages caused by lime deposits. Available in roll or sheet form.
Platon Plaster Base
A BBA certified membrane featuring a unique undercut stud design that creates a mechanical key for plastering. Single component with no mesh layer, Platon Plaster Base can be installed on internal walls and vaulted ceilings above or below ground level. The substrate remains visible through the clear membrane for precise fixing. It is suitable for use with sand and cement renders and most lightweight and renovating plasters.
An economical 5mm HDPE cavity drain membrane that is impermeable to water, gas and water vapour and suitable for installation on walls and floors, above or below ground. P5 can also be used above ground to isolate walls that are damp or contaminated with salts.
Platon Plaster Mesh
An 8mm HDPE studded membrane with integrated mesh layer for direct plastering. As with other Platon membranes, Platon Mesh can be fixed directly to existing wall finishes without the need for extensive hacking off or preparation.
Platon PB2 Mesh Membrane
A 3mm polypropylene cavity drain membrane with integral mesh layer making it suitable for direct plastering. Suitable for use as an isolating plaster membrane following remedial treatments.
Platon Double Drain
A membrane system for external basement walls which protects underlying waterproofing from backfill damage. The filter fabric layer ensures soil cannot enter membrane cavities and impede drainage.