Description

Cavity Drain Membranes
the general principles...

Almost all basement structures are likely to be subjected to water pressure during some period of their life. BS 8102:1990 considers that "drained protection", in other words, a cavity drain membrane fitted to the structure, is the most effective and trouble free type of water resisting construction.

Cavity drain membranes provide an alternative to conventional cementitious tanking systems, which work by holding the water back. Cavity drain membranes work on the principle of allowing water to continue to penetrate the structure but control it in the air gap and divert it to a suitable drainage point. They do not allow pressure to build up against the internal construction and the air gap behind the membrane allows the structure to breathe and to some extent dry out.

The 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. This method of waterproofing allows decoration and floor finishes to be completed almost immediately, without long drying out periods.