For a reliable installation of a shower channel or drain in the floor there are flexible membranes deliverable which are not porous. These membranes are made of non woven polyester material and foreseen with butyl adhesive for a waterproof connection of the shower channel or drain. On all membranes there are cut outs of the channel or drain, so they always fit perfectly.
The minimum overlap of the membrane is 80 mm so the critical connection is always guaranteed. The top of the membrane can be glued with tile adhesive.