mold .. questioning hole behind shower panel

[ma740988]

Roughly 3 months use on a bathroom I remodeled and I'm observing mold on the caulk. Grout is Ardex FL and the caulk is Mapei Mapesil T Silicone caulk.

There's a hole behind the shower panel as shown in one of the pics below. The question: Seems too 'early' to be having mold so one thought is I could have moisture build up behind the walls from the hole behind the shower panel. True/False? If True I see two options.
a) (easy) caulk around the shower panel
b) (hard) redo the plumbing and instead have two hole for pvc pipe out the wall, then add shutoff values.

An aside: The 4 individuals using the bathroom run the water at 39 to 41 degrees C so a lot of moisture is generated

[ss3964spd]

You mention mold on the caulk, MP, but not specifically where. Knowing where might help us home in on what might be causing it.

Four people using the shower; how many uses does the shower see per day?

[ma740988]

Knowing where might help us home in on what might be causing it.

The 'spots' were observed in two areas.

1.Assuming you're facing the shower panel. Right corner wall about a 15 inches up from the shower floor
2. Curb base where curb meets shower floor.

Bleached the areas and life is good but I suspect the mold will return and I'm still questioning if the issue is the hole behind the wall.

Four people using the shower; how many uses does the shower see per day?

2x

[ma740988]

I've attached two photos. One showing the view from the clamping and the other showing the view from the drain base. For simplicity I used a size A paper to represent the shower pan liner so the white spots you see is the paper representing the 'pan liner' that was folded down.

When the shower is not in use I observe water about a foot down in the 2 in drain pipe. IOW water settles in the pipe. No issue here.

When the shower is in use the water rises to the surface of the drain (the shower floor essentially) and that concerns me. In this case the water has an option to enter above or below the pan liner. IOW as the water rises, water will enter the area where the pan liner (white paper) is folded between the base and drain flange.


1. For starters there's no signs of a clogged drain but is it normal for water to rise as it enters the 2 inch pipe? I suspect the answer is yes because of the volume of water entering the drain

2. There's nothing fundamentally wrong with the install of the shower liner, drain flange and clamping ring - it's a pretty straightforward process - but before starting over and perhaps going the kerdi route is it typical for water to rise and enter the underside or top of the pan liner?

Thanks in advance

[cx]

This is the shower with the mold problem, MP, or are you building another shower?

There should be no issue with water from the drain traveling back into the floor so long as the liner was correctly installed with a bead of silicone sealant on top of the bottom drain flange when the liner was installed.

If you see standing water only two inches below the drain opening, your P-trap weir must be installed very high and having water build up at the drain would not be a surprise. It should drain away quickly when the source is shut off, though.

You installed this drain plumbing?

My opinion; worth price charged.

[ma740988]

Cx as always thanks for the responses.

This is the shower with the mold problem, MP, or are you building another shower?

Correct on the mold problem. I'm starting to think I found the problem.

The wife complained last night about how she removed the drain strain, cleaned it yet the water seems to be draining slowly. I wanted to understand what 'draining slowly' meant so I removed the drain cover and strainer, turned the water on and thought it was odd that the water wasn't getting through the 2 inch pipe and the p-trap fast enough.

There should be no issue with water from the drain traveling back into the floor so long as the liner was correctly installed with a bead of silicone sealant on top of the bottom drain flange when the liner was installed.

10-4

I followed the Oatey video. Added the silicone to the bottom flange. In the Oatey video they added silicone under the pan liner but I skipped that step.

If you see standing water only two inches below the drain opening, your P-trap weir must be installed very high and having water build up at the drain would not be a surprise. It should drain away quickly when the source is shut off, though.

You installed this drain plumbing?

Yeah but my install was literally adding a new drain flange. Cut the old one off, made a small adjustment to the pipe and placed a new flange on.

Having said that, I just did a test on another bathroom i have opened up. For this one i'm using the kerdi system which is an entirely different animal in terms of how you install a drain , nevertheless, I'm able to hold the garden hose above the drain and it never backs up (water is not rising) so I'm starting to think there's a clog in the p-trap on that other bathroom. Time to pull out the snake.

[cx]

Originally Posted by MP

There's nothing fundamentally wrong with the install of the shower liner, drain flange and clamping ring - it's a pretty straightforward process - but before starting over and perhaps going the kerdi route is it typical for water to rise and enter the underside or top of the pan liner?

Originally Posted by MP

I followed the Oatey video. Added the silicone to the bottom flange. In the Oatey video they added silicone under the pan liner but I skipped that step.

I'm getting confuseder and confuseder. Applying silicone sealant to the top of the bottom drain flange is the same place as applying silicone sealant under the pan liner at the drain. What am I missing here?

Properly installed, the drain/liner installation will never allow drain water to enter below the pan liner even should the receptor fill to overflowing.

My opinion; worth price charged.

[ss3964spd]

Originally Posted by MP

I observe water about a foot down in the 2 in drain pipe

If water "settles" that far down in the riser after the running water has stopped it definitely should not rise back up that far unless you're exceeding the GPM rating of the drain system. 2" system would need about 30 GPM.

[makethatkerdistick]

I agree with Dan. A 2 in drain pipe has a very high capacity. Water should not rise up during use in a typical install, even if it were fed by a 3/4 in line. Maybe you have a partial clog somewhere down the line? Or it could be a venting issue.

I recommend the use of a strainer inside the drain body. Needs to be cleaned more frequently but will keep those drain pipes clear.

[cx]

Good eye, guys. I had read that as him seeing water 2" down the drain riser rather than a foot down. You're certainly right that shouldn't be no steenkin' water rising up to the top of the drain during shower use.