Our builder claims in Florida, where there is a code that one-story houses on concrete slabs do not need a membrane for the shower. And the 2-inch gap between the durock and the floor is there to prevent “whicking” for the durock that is not actually waterproof.
So, there is no membrane, and the 2-inch gap is in keeping with the code. And that it is actually the tile and the grout that make things waterproof. If there is any leak into the walls, it is because the home owner did not maintain the seal in the grout.
Common sense says: no membrane, open space means trouble… I’m needing advice on how to get our builder to fix this problem. THANKS!
When creating a waterproof system, it is imperative to build a waterproof system that does not depend on grout and caulking to keep the water out. The 2-inch gap is way too wide and will leak. Years ago, best practices included installing a waterproof barrier under the concrete board. Even that system had problems due to the fact that when the concrete board was screwed to the studs, the screw would penetrate the plastic, creating an entry point for water. The current solution is to install cement-board, plywood or foam-board panels directly over studs – no vapor barrier. Then, seam tape all long joints and seal corners with corner kit. Next, two coats of waterproofing is applied over the entire area pf panels and floor. The idea is to fully waterproof the area before the tile is installed. Even if the grout fails, it will still be waterproof.
I like ARC waterproofing system but Wedi and Schluter are also excellent. As far as communicating with your contractor, I always find open friendly conversation works the best. If they are not willing to make the change to correct the situation, pay them for the work and materials to date and hire a more experienced company.
No, all surfaces should be waterproofed fully. Grout is not waterproof even with a coating of sealer. We use Schluter Kerdi Membrane to waterproof all surfaces and installed properly, it should never leak. Your description of the work is not according to code or best practices.
There would be definitely problem and the black mold would be first. He could still fix it with Kerdi/Shluter product, since it is applied on top of cement board with out fasterners prior tile installation.
If there is gap to prevent moisture wicking. It should be at the top of some sort of pan. A noncoupling membrane should be used it doesn’t transfer moisture and will provide the water proofing needed if installed properly
Apparently a mistake has taken place, 2" gap will leak. Always it is best to have a membrane under all shower bases, Dura rock should not touch the ground or the edge of the wet surface 1" max space is ok.
Easy to fix.
There should not be any Gap, usually in Florida when the slab is poured the shower floor is recessed 4 to 6 inches lower than the rest of the bathroom floor. The shower has to be framed out and there is a pressure treated floor plate is installed and the the wall studs. At the time of tiling the studs and the floor plate should have a liquid rubbery substance “painted” on it ( Red Guard, or a comparable brand) at least the first bottom 12 inches. This "paint goes on thick and when dry acts like a rubber sleeve. Then the cement board should be installed in such a way that it overlaps the concrete slab by about 1 inch, and the joints of the boards should be taped with a waterproof membrane tape and then every surface area, ( Yes the ceiling also) , should be painted with the same rubberizing paint. Some builders would say that this is over kill, I say its complete protection
