This shower had a moisture barrier drywall installed for about 1 year as a backer board for shower. This is not an approved method of installation! Outside of the shower would have been fine, but not inside. It is not difficult to see how much water the drywall absorbed in this period of time. The customer paid to have the job done twice!
The shower pan was not installer correctly. The costs to repair and replace ended up costing the customer nearly 2 1/2 times what the original job. This job required removing all the tile, backer board and mold treatment.
The photo is of a shower curb. There are a few things incorrectly installed. The installer used corrosive fasteners. You can see that they are rusting and at some point will fail. The other thing to point out is that fasteners should never penetrate the shower liner.
This shower pan liner was cut in the corners by the installer. This is a major problem right from the start. A shower is said to be exposed to more water than our exterior gutters and down spouts. This shower was set up for failure right from the start.