The Importance of that Space Between Wall and Floor Joint
A big factor in having a good waterproofing system is that there has to be an opening to drain the water from the walls. Wall leaks include pipe penetrations, flooding window wells, condensation, leaks from wall cracks, and other sources. Of course, any homeowner wants to fix all the leaks they see with the original installation – but to play it even smarter they should address leaks that could possibly spring up in the future. A gap at the edge of the floor will catch any leaks, prevent the floor from getting wet, and prevent damage to anything that is on the floor.
This gap is sometimes called a French drain, although those who know a little commonly use this term to mean different things. The gap along the wall can be made by sticking a piece of wood between the floor and wall, concreting up to it, and pulling it out. This makes a big ugly gap that can fill up with debris from the floor.
A better way is to have spacers along the backside of a flange that sticks up above the floor. The optimum size for this gap is 3/8 inch. You want it to function, and look like it’s supposed to be there, not like a big mess.
Beware of systems that say they have a flange that is tight to the wall and yet takes water from the wall. It does not take a waterproofing specialist to know that is not possible.