Jadnashua
Retired Defense Industry Engineer xxx
If you test your plumbing before you close up the walls, and it is done in a workmanship like manner, what percentage of times does it leak? Practically zero. Why is it such a stretch to understand that, properly done, the plumbing isn't an issue.
The same thing with your installation of the Kerdi and various components (Kerdi-band, various seals around penetrations, etc.). The major one is the pan...if it does not leak when filled nearly to the top of the curb during the flood test, when will there ever be the same water pressure and volume of water there? On the walls, where you may have any one of the approved boards, it's pretty simple to ensure you have at least a 2" overlap of the material. It's not really very hard to place the material properly.
Your argument of poking holes in things comes down to workmanship...if you did it in the pan, what's underneath there may not be directly affected in the pan, but it would still affect the subflooring. You tear it, you fix it...once it is covered with tile, it isn't going to magically get a hole in it.
On the walls, while nothing is impossible, it's much harder to poke a hole in things, and again, after it is covered in tile, how much ever really gets through the tile or the grout and into the thinset with any pressure? Almost none, and unless the shower is used 24/7 with a shower spray directed at it, it has the majority of the day to dry out towards the surface. Any bigger holes would hopefully be seen before they were covered up with tile. So, even a small puncture on the wall (which should have been fixed) has negligible chance of damaging anything. On the walls of a shower...how far do you think moisture penetrates underneath a tile on a surface membrane like Kerdi? You'll typically have maybe 1/8" of thinset covered with tile and grout...it can't hold much water, and with gravity, why would it be there in the first place? At your wall/pan junction, you have at least two layers of Kerdi assuming you seam it there, with at least a 2" overlap that was tested during the flood test and verified it didn't leak...why would that more vulnerable area leak?
The example was given about cracking the el the shower arm is screwed into...certainly that could happen, but how often? Maybe when first installed, but then that's easy to check - cap the end, and turn the water on and listen.
Same idea with the tub spout, should that be in question, although many of them do not use an el and a nipple.
Water damage to the substrate in a properly installed Kerdi shower system is highly unlikely. Just like playing Powerball...there's a chance to win, but not a good one. The odds of a Kerdi shower failing is pretty low. IMHO, any leak in your shower needs repair, and if it does, that often entails some tearout.
There's risk in any endeavor in life...the only ones you'll win on are that eventually, you will die. The risk in a properly built Kerdi shower is low enough to not be an issue IMHO. If you do not feel you have the skill to do it with drywall, fine by me.
Properly built...they do not leak, everything stays dry, no problems. You'll likely have a roof leak damaging your drywall ceiling or walls before your shower.
The same thing with your installation of the Kerdi and various components (Kerdi-band, various seals around penetrations, etc.). The major one is the pan...if it does not leak when filled nearly to the top of the curb during the flood test, when will there ever be the same water pressure and volume of water there? On the walls, where you may have any one of the approved boards, it's pretty simple to ensure you have at least a 2" overlap of the material. It's not really very hard to place the material properly.
Your argument of poking holes in things comes down to workmanship...if you did it in the pan, what's underneath there may not be directly affected in the pan, but it would still affect the subflooring. You tear it, you fix it...once it is covered with tile, it isn't going to magically get a hole in it.
On the walls, while nothing is impossible, it's much harder to poke a hole in things, and again, after it is covered in tile, how much ever really gets through the tile or the grout and into the thinset with any pressure? Almost none, and unless the shower is used 24/7 with a shower spray directed at it, it has the majority of the day to dry out towards the surface. Any bigger holes would hopefully be seen before they were covered up with tile. So, even a small puncture on the wall (which should have been fixed) has negligible chance of damaging anything. On the walls of a shower...how far do you think moisture penetrates underneath a tile on a surface membrane like Kerdi? You'll typically have maybe 1/8" of thinset covered with tile and grout...it can't hold much water, and with gravity, why would it be there in the first place? At your wall/pan junction, you have at least two layers of Kerdi assuming you seam it there, with at least a 2" overlap that was tested during the flood test and verified it didn't leak...why would that more vulnerable area leak?
The example was given about cracking the el the shower arm is screwed into...certainly that could happen, but how often? Maybe when first installed, but then that's easy to check - cap the end, and turn the water on and listen.
Same idea with the tub spout, should that be in question, although many of them do not use an el and a nipple.
Water damage to the substrate in a properly installed Kerdi shower system is highly unlikely. Just like playing Powerball...there's a chance to win, but not a good one. The odds of a Kerdi shower failing is pretty low. IMHO, any leak in your shower needs repair, and if it does, that often entails some tearout.
There's risk in any endeavor in life...the only ones you'll win on are that eventually, you will die. The risk in a properly built Kerdi shower is low enough to not be an issue IMHO. If you do not feel you have the skill to do it with drywall, fine by me.
Properly built...they do not leak, everything stays dry, no problems. You'll likely have a roof leak damaging your drywall ceiling or walls before your shower.