I'm sure Bill or Mongo will describe this in much better detail than I can... but basically I think that you shouldn't worry. The waterproofing of the shower pan is underneath all the tile, grout and thinset. The grout isn't supposed to be waterproof. Natural stone, like marble, isn't waterproof either. Water gets though these porous materials and hits whatever waterproofing membrane was used when the shower pan was built, and flows down to holes in the drain apparatus. Our shower floor is a marble mosaic and some of the joints between the tiles are so tight there's no way they're 100% filled with grout, but I've been told that's fine since the grout isn't supposed to keep water out, anyway.

This is my understanding, anyway, of the magical world of shower tile! Good work isolating the leak to the shower doors, by the way. Was water getting into the wall at the hardware/fasteners, or what?

Staceyneil, thanks for the reply. I actually called the tile guy that regrouted my walls. He basically said the same thing as you. That the pan should take care of any water getting through the grout. But since living in the house for a year I have found things that the builder either did wrong or he cut corners. So I was just worried about how he built the shower. So I really have no idea what he used to build the pan with.

As for the shower door. Once more thing that I did after blowing up the balloon to test the pan was to put a shower curtain on the inside of the door. This way when I showered no water could hit the shower door. When I did this the toilet paper stopped getting wet. So that is how I knew it was related to the shower door.

So I started looking at the shower door. Well sure enough the previous owner has caulked over the weep holes in the shower door. So I thought to myself, where is the water going that gets into the bottom door track?? The threshold that the door sat on was not tile, but one continous piece of corian. There was caulk on each side of the threshole where the corian met the tile wall. So when I took the door off there was a small hole in the caulk right where the bottom track of the door met the vertical track of the door that goes up the tile wall. There was also a small gap between the bottom track and the wall track of the door.

So to make a long story short. I think what was happening was water was getting into the bottom track of the door, leaking through the small gap between the bottom track and wall track, through the small hole in the caulk, and then leaking into the drywall.

I'd be more curious about what's causing the grout to crack.

Bill, I did think about that. I imagine there is no way to find this out without ripping up the tile shower floor, right? Now everytime I shower I swear that when I step in certain spots I can fee the tiles moving. But I don't think they really are. I think I am just paranoid.

It's possible. When grout cracks, that suggests movement of one sort or another. Being that the shower pan's really not attached to the structure at all, except at the drain, it can't be from structural movement. I'd be worried about the mortar bed under the tile. If it wasn't mixed properly, or if not enough portland cement was used (or even if TOO much was used), it could be cracking, either from shrinkage (if too much) or powdering (if not enough, or if the mix was dry). One way or the other, I'd be concerned.

Bill,
So what would you recommend doing? Having someone come up and rip up the shower floor to see what is going on? Can they do this without ripping up the walls of the shower? Or will they have to take off the first row of tiles on the wall. Problem is the house was built 10 years ago and we aren't the original owners and they didn't leave any extra tiles!!!

Do you have any questions I could ask a tile contractor so I know that they know what the hell they are doing? Just want to do as much due diligance as I can so I don't get burned.

Try this-- get a butter knife, and take the butt end of the handle, and tap around the shower floor. If it sounds hollow or soft as you tap around, you might want to call someone in to look at it.