My insurance company is refusing to pay for what I would call the self-destruction of a shower resulting from a series of shortcuts taken by the builder -- years before we bought this pre-owned home. For backer-board they used greenrock, which may have been a code violation, even in 1995 when the shower was built. Anyone know for sure? There was no subfloor or subpan under the pan liner, nor was the bottom half of the clamping drain recessed into the foundation. Thus, there was no slope to the pan liner, and water in the pan liner accumulated to about 1/4" to 3/8" in depth before reaching the weep holes. There was no pea gravel or other material used to prevent the weep holes from clogging with pan mud when the pan was laid, and the builder obviously did not even try to stop the mud from clogging the holes. Mud was jammed through the weepholes down into the drain. If the weepholes drained at all, they drained only very slowly, slow enough that what I believe to be a lower than normal amount of seepage through very well-sealed grout still resulted in water backing up inside the liner. (After months of not using the shower, the pan was ripped out and found to be quite wet. There were lots of ants and centipedes living in it. Tons of mold.) Before ripping the shower out and finding all these problems, I dried it out a couple of times. I stopped using it and cut an access panel in an adjacent wall, from which I could put my hand into the liner and feel several inches of standing water. I syphoned that off, stopped using the shower for weeks, and resealed the grout. The pan took a few weeks to fill up again with water -- my grout was very well sealed -- but when it did, the greenrock, which extended to the floor on all sides of the pan, was sitting in 3 or 4 inches of water. The pan liner always held water perfectly except at the dam/threshold. In forming the pan liner around the dam/threshold, the liner was slit down below the top of the pan, and screws or nails were driven through the pan liner below the top of the pan. As if that were not bad enough, no patches were made. No preformed corners were used, no "welding" with a solvent. Instead, swatches of liner material were simply laid over the cuts before the backerboard was put up. Eventually, the tile walls buckled and caved in, revealing some termite damage in exterior walls, which I know insurance won't cover, but also an astounding amount of rot in one interior pony wall. I don't know whether homeowners insurance will cover "self-destruction caused by shoddy workmanship", but my guess is that the installation of the liner around the dam/threshold is my best argument, since they might cover a leaky pan liner. Unfortunately, my insurance company (USAA) is balking. The "expert" plumber they are relying on doesn't know that the pan and the pan liner are different things, does not install a sloped subfloor/subpan below the liner or recess the drain, claims clogged weepholes don't matter because the pan mud is permeable (and admits that he does not protect the weepholes when building a shower), claims no water will get into the pan unless there's bad grout because grout is not water permeable. It's a nightmare. I know more about shower construction than my insurance company's expert. Any suggestions would be appreciated, especially on dealing with the insurance company.

Silly question. I am installing a corner shower and am planning the drain. Got that part. I'm wondering how, after I position the base and insert the drain into the 2" pipe, (how) I can "get under the floor" to tighten that large PVC nut that pulls the top part of the drain to the base. This screw on nut that I'm writing about is the one that came in the box with the drain. Thanks!