I have a basement that I want to fix... paint a membrane in the shower corner? The house is drained but not the floor... so I was planning to skip the membrane in the toilet when I tile, but the question is just about the shower corner... grout and fix breathe well, so it won't be such a big problem to lay tiles in the toilet... it's just the shower corner, should I lay the membrane on the floor and the wall where the shower will be or just the walls or whatever it should be... any tips?