Are cracked threshold tiles an indication of improper installation of my shower system? Even when they show up at year 7?
I have a large 6+' x 4+' curb-less shower. Contractor used 6" wide by 12" long ceramic tiles at the threshold (and same tiles on the walls). The threshold is raised higher than the adjacent shower and bathroom floors. One inch bullnose trim tiles were used on either side of these threshold tiles to bridge down to the adjacent shower and bathroom floors. These are all grouted along the two floor lines. The shower was a hot mop installation. There is a fixed glass panel on one side of the threshold tiles and a hinged glass door on the other. After 7 years these threshold tiles are cracking, starting at the glass door side and traveling in a continuous line the length of 4 tiles and into the hinged panel side. That leaves only two tiles not yet cracked. The crack is running more or less parallel to the adjacent floors. This is a production home built in California.
This shower drains to the back wall, where there is a 5' flat bottomed recessed linear drain trough several inches away from the back wall with a center drain. The bottom of this drain pan is level and has no slope. The shower floor was "redone" by the builder shortly after the house was completed due to poor slope. The water drained towards the threshold and not towards the back wall. I don't know what exactly was done during this repair other than some of the floor tiles were replaced. I was told that the tile contractor would build up the mortar under the floor tiles, that he had plenty of room to do this, and that he would use a bonding agent to cement the two levels of mortar together. I was also told that the linear drain channel by design does not slope. During this repair the linear drain was not touched and the hot mop was not redone. None of the large threshold tiles were removed and I don't believe any of the bullnose trim tiles were removed. I don't even think that all of the floor tiles were removed, just some of them.
This repair improved drainage but I believe the slope is still defective. There is now a slightly raised "hump" about 1 foot by 1 foot where the shower water hits. Some water goes towards the back wall and the drain, some towards the threshold and some everywhere else. Given that it's such a large shower, there is a fair amount of "drainage by evaporation."
Are these cracked tiles a big deal? Can this be repaired by filling the cracks with epoxy? This is what the builder now offers to do. Should I have an independent, experienced tile setter look at the installation? Thanks.