All of us make mistakes; it’s going to happen, but the crucial point is how we handle them. Do we learn from our mistakes, make the necessary changes and improve, or do we continue to make the same mistakes and suffer continuous failure? Think about it.
As we look at this failed shower, which was only 12 years old, you may ask, did it leak? Was the structure damaged by water? Did the water lay in low spots and fail to find its way to the drain? The answer to each question is no. So, what was the problem? The homeowner’s complaint was that the shower smelled really bad. Could a significant odor be caused by a faulty installation? The answer is absolutely.
Overall, the original installer did a pretty good job, but the items which were done incorrectly were significant.
Starting from the bottom up, we see evidence of water on all sides and something odd on the shower floor. Why was there ½” cement backer board on the floor? The plumber had installed the drain properly, but apparently, the installer didn’t know that a pre-slope or sloped fill needs to be placed on the subfloor to pitch the water to the drain at the plumbing code requirement of ¼” per foot. Not knowing this, and the fact that he thought the drain was set too high, he installed the backer board to make the floor flush with the drain body. Problem solved! No, problem created.
In what is known as a conventional shower base, or a water in/water out system, the slope to drain is the pivotal component to success. Without slope to the drain, the water lays flat on the floor creating a reservoir of stagnant water that is the same depth as the drain flange. The real problem is that it is impossible to evacuate this water. It is there forever. Through use, soap, shampoo, cream rinse and body oil mixed with this stagnant water, eventually turns into a biological septic tank. This growing bacterium is the source of the odor.
Problem number two was the curb which leaked water into the subfloor. The installer did install the shower pan membrane correctly until he got to the curb. Nailing backer board through the membrane is a certain failure. To overcome this mistake, he coated it with a liquid- applied membrane, which will work if properly applied. In this case, not following the manufacturer’s written instructions, it also failed.
Problem number three was the seat, which was dead level, allowing water to puddle over its entire length of five feet. Had the seat been sloped at the same rate as the shower floor (1/4” per foot), it would have survived. Here too, the installer thought his project would succeed if he coated the seat in a similar way to the curb. The liquid-applied membrane will work when done correctly, but not this time.
The moral of this story is that getting a shower installation “close” to being within the ANSI standards, TCNA Handbook guidelines and the manufacturer’s instructions is not good enough. Do it right the first time and succeed.