I installed a custom shower 44" x 84" about 2 years ago. The shower floor is 2"x2" natural slate and the walls are 4"x4" porcelain. The shower floor has 2 drains and one of the drains is sloped perfectly and it works well. The other drain has a problem in that a small 6" x 6" section in front of the drain collects a puddle during the shower. I used "goof-proof" shower slope kits to ensure that this wouldn't happen, however, I believe the "natural slate stone" has some highs and lows that has prevented the water from reaching the drain.

A few weeks ago I started to notice a musty smell in the shower. I've cleaned the floor and drains thoroughly and that doesn't appear to be the problem.

My thought is that the water that has been setting immediately after each use of the shower has worked through the grout/stone and is trapped underneath the floor. I haven't sealed the floor since I installed it so it is time to do that as well. However, I'm concerned about sealing the floor and locking the moisture below the surface of the floor. At the same time, a good sealer may prevent water from passing through the floor and it may correct the problem. Any suggestions?

Before I used a sealer on the floor I would scrub it down good with full strength bleach to kill bacteria and remove mold and then let the slate floor dry out completely. Good luck, Tom

HI I have done stone and marble for years on quite expensive homes, and my question is did you use a pan liner before putting in your shower as I have seen people not do this and not realize that grout absorbs water and even sealing the grout lines will only last awhile and is designed to be water resistant not waterproof. If this was not done the water has soaked through to the wood floor and your smelling the rotting wood which will not dry up as it isn't exposed to any air. It will have to have the floor pulled up and the liners put in before the rest of the pan is installed and it has to be sealed and sloped to the drain that way any moisture that goes through the grout will still drain. If you do have liners were they inspected overnight to hold water and not leak? I myself have had to redo my own liners occasionally before proceeding. Otherwise the smell could be hair and soap mildew buildup.