Newton often sees designs from those new to cavity drain waterproofing that show a 20mm stud floor membrane laid above a level raft or slab.
This is a dangerous method of the use of cavity drained membrane as the membrane does not have the ability to resist water pressure. A few millimetres of water pressure is enough to see water pass through the seals and joints.
Another problem with this method is standing water over a new raft or slab will draw out the free lime from the concrete. This can lead to substantial lime scale deposits, often enough to block the 20mm cavity.
In all cases, Newton 106 Lime Inhibitor should be applied to concrete surfaces to prevent the leaching out of free lime.
We would recommend the use of the Newton Basedrain drainage Channel as a safe, competent solution to cavity drain waterproofing. The channel is placed either below (in the case of a wall kicker joint) or above (in the case of construction joint to the raft or slab) the joints of structure. This acts to intercept the water as it enters the structure.
These drainage channels allow the water to travel directly to the sump and not over the expanse of the raft or slab. The channel network is safe and easily accessible.