[Phelps]

Do you have a 4-piece shower stall (3-sides and the base?)? If so, the water could be getting in the *vertical* joint(s) [usually the front one], from bouncing off your body (perhaps hers more than yours because of your differing shapes or where she stands, and it runs down inside the joint and then gets behind the caulk you have at the top of the base pan. Once behind up there, it can run ontop the lip of the shower pan or "curb" and be behind the 'tile', as you call it. Then at the front of the shower where you step over the curb, the water will leak out between there and the sheetrock.

I have had to make *many* a wall repairs due to this scenario. Many shower stalls (and bathtubs) never took into account this scenario. I have only seen a couple brands that have taken this into account and made proper channels ontop the "curb", which allow water to run back into the shower pan if trapped back behind the tile, up on the curb.

Trying to surface cure your problem with caulk is always a tough problem. What usually happens is water gets back there somehow in time, due to expansion/ contraction, cleaning the shower and pulling away the caulk or having it come loose (All it takes is for the bond not to be there.) It may even look sealed, but if the bond is not there it can leak. Usually if it leaks in a caulked joint, you will see black mildew in or behind the caulk and it can't be totally eradicated with bleach when this is the cause.

The proper way is to really not have caulk at all!, and simply create a situation at the top front of the curb which will not allow this water from leaking out, (It can be done.). I have solved the problem by silicone caulking or Household Goop type epoxying the joint formed at the front between the top of the curb and the bottom of the 'tile' so that water cannot continue by and running out of this joint! You have to remove the wallboard at this area to do the job correctly. Then mud it back in with a good setting type mud which then will keep pressure against your caulk and not allow the water to leak out.

The primary source of the leak getting back there could also come from a poor seal around the big chrome trim plate that goes around your single handle mixer valve. Do not simply surface caulk around this (at is will not last). You need to remove the mixer control knob and big chrome trim plate. The back side should contain a foam seal strip that goes about 3/4 of the way around it. You never want to have the bottom sealed in case water does get in there. When I have this stuff off, I clean the hole area good with Easy Off Max blue-can (*not* the yellow can stuff!!!!) oven cleaner (It does not wreck anything and is the best soap scum remover bar none!. I have talked to company representatives about this years back before they came out with their BAM line of products!). Then ,after you rinse and dry, take silicone caulk and apply a thick bead around that hole, 3/4 of the way around it, leaving the bottom under the hole alone, to allow water to weep out *if* it ever got in there. Then replace that which you took off. This will solve this as being any current or future source of the leak, for you. If the water is leaking in there, it would be winding up behind the wall up on that "curb", and leaking out like I explained.