There are different ways to make basements dry and this is one of the most critical aspects of a successful basement. The waterproofing falls into 2 main areas, cementitious tanking, or a cavity drain membrane system.
The difference is a tanking system is a slurry that is applied to the walls and working on the principle of stopping the water entering the basement. The disadvantages of this system are, it is only as good as the surface it is applied to, and often this is brickwork that is 100 years plus old with little inherent strength. With a build up of water behind the tanking the bricks are liable to delaminate. Also building move and settle over time, a dry summer or a water drain being replaced in the street may create some building movement, this may result in a crack to the tanking system, which will render it ineffective.
Cavity drain membrane system
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 to dry out. The membranes are lose 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.