Grouted pebble shower floor, tile walls. The rough, cement-like grout where the floor and wall meet, which resembles the banked curve of a race track, is slowly disintegrating, and there are gaps in some spots where water is certainly leaking. Can I simply mix some grout and recreate the "bank" of the seam all the way around the shower? Should I first use non-silicone caulk or sealant, and then use grout?
The grout is disintgrating because it should have never been used where the floor meets the walls or where walls meet walls. These different planes shift and will crack grout. Caulk should be used instead, it's flexible. Get a grout saw and remove the grout at these locations and replace it with a high quality caulk.
Grout is not waterproof. (Some grout in a perfect bubble is waterproof, until it moves.)
Grout will deteriorate over time if water is trapped beneath it. So either your grout is not waterproof or there are cracks in the grout next to the tile allowing water in.
You should have something under the tile/grout that is doing the actual waterproofing. Meaning the failing grout while it may be messy or whatever should not effect the shower failing.
That being said...
I have installed or supervised many high end showers. You have river rock with HUGE grout lines. No big deal because there is probably ditra under it or something similar.
Then what is the issue??
They didn't take literally 5 minutes to hit the wall connects with clear silicone. That's it. You have too much water getting into the wall connects. You need to let this dry out - 1 week - and hit all of the connects with a nice small bead of clear silicone (GEII). You are going to be surprised at how easy and effective this is.
Note: You do not have to remove the grout unless it is completely unsalvageable. If it is solid you caulk the corners over it. If it is in that poor of shape you need to regrout the areas and then caulk.
