Should I unscrew the nut and Plex piping from the Kerdi board to add my Cobbe shower head arm and flange after tiling, or is it necessary plumbing?
Asked by Judy Simmons 
5 months ago
Last Updated: July 26, 2024
Could use some quick plumbing advice (fingers crossed)
Got the rough plumbing sorted and installed Kerdi board. But I’ve got this massive nut and Plex piping poking out from the board right where my shower head should go.
Before I tile, should I just unscrew this when I’m ready to add the Cobbe shower head arm and flange? The coupler/drop ear looks like it’s in the right place, just unsure about this extra plumbing bit.
Seems like an experimental nipple
The plumber kept it on to prevent water from shooting out of the drop ear when turning the water back on, or maybe for testing purposes. Everything will be back to normal once it’s all done.
Yep, probably left on for a pressure test.
Sure thing! Your shower head arm should screw in with no issues. Just make sure to use pipe dope or plumber’s tape when you attach it.
Yep, simply unscrew it and you’re all set. Just double check that your water is turned off though haha
The additional pipes are there for the pressure test. Just work around them and leave everything as is until the plumbers come back to finish up.
Just a quick pit stop
This is just a temporary plug and not a reliable one. It’s not recommended to use pex in this case as it may spin on the fitting, making it hard to remove after tiling. I suggest buying rough-in nipples from Lowe’s and installing them before tiling
Unscrew it now and grab the yellow rough-in 6” plastic plugs, they even include a black rubber washer. This way you won’t damage the tile later on. Also, seal the cut in the board with rubber sealant as a precaution
It’s only temporary. Remember to keep it in place while tiling to prevent anything from entering the plumbing
I opted for a capped nipple…I’m a plumber and don’t want any trouble removing it later. But hey, whatever works I suppose haha
Get rid of all the clutter and simply install this
Kevin s, your photo speaks volumes, much appreciated!
Could that be a 3/4 to 1/2 reducer? Any particular reason for using it?
Seems like somebody placed it there as a trial for the line. Usually, you wouldn’t need to use that pex. It already has an inlet that most plumbing faucets can screw directly into with some plumber’s tape for a proper seal.
That’s necessary for the test to meet inspection requirements, assuming you’ve already had an inspection.
Is that a 3/4”x 1/2” fitting? Did you accidentally use a 3/4” drop ear 90 in the wall instead of 1/2”?
To conduct a pressure test, turn off the water and uninstall
My guess is that someone didn’t have a test plug and quickly improvised one. So, yeah, simply remove it when you’re ready and proceed with installing your shower arm