Tile walk in shower problems

We had our home built five years ago. We had a 4 x 6 walk in tile shower Put in place of the whirlpool tub that was to be installed. I have done several tile showers and many floors in the past with great success. I just didn't have time to do the shower at the builders pace. Anytime I have installed a tile shower I always did the floor first so the sides would overlap the floor. Our builder's tiler did the walls first then installed the floor. There was a caulking gap around the entire outside of the floor where it met the wall. I figured he knew what he was doing more than me because I only do it as a hobby. In the recent month I've noticed very small separation of the grout in one area and within that month it has extended about 10 inches. Also in the pictures you can see how the caulking has separated slightly and now allowing some mildew. We try to keep up with keeping any mildew out of the shower. I also have learned that the shower will overflow into the basement if the drain is clogged in the trap or if a lot of water goes down quickly. This tells me the rubber wasn't glued to the drain or the bolts weren't tightened enough on the drain. Fortunately I have full access to the floor underneath and can see there is no water damage. I have attached some pictures and really need some advice. If this needs be done I will plan to do it myself. Unfortunately I won't have enough leftover tile to replace the sides if I were to remove the first section of tile and the floor. I really don't want to redo the whole thing. ugh. I don't want to do any of it think I can clean out the joints and bandaid it for a while until I have a week off?. Thanks for any help.

 

I'm not a tile guy but like you I've done quite a bit of tile including a half dozen showers. And I agree that the wall tile should wait until the floor is done.

What kind of grout did the tile guy use on the floor/wall joint? I think part of your problem may be that it is a new house and you're seeing the result of some movement as the house settles.

I would clean out the existing grout and use either a flexible grout or a sanded caulk.

 

Walls first, floors last, it really doesn't matter.

What matters is that you have a waterproof system behind the tiles that does not allow water to leak.

The cracks at the corners are common, any plane change is susceptible to cracking that is why you use caulk, not grout in the corners.

That separation in the grout on the floor is concerning why it happened but it could be dug out and repaired.

The most concerning thing you mentioned is that you get a water leak if drain is plugged, that indicates your waterproof system has/is compromised and there is no simple repair for that short of tearing out the floor, maybe some of the wall depending on what you see so that it can be fixed!

 

Thanks, guys for your valuable comments.