Why does drywall work in a Kerdi Shower?

Discussion in 'Shower & Bathtub Forum & Blog' started by jadnashua, Jan 26, 2014.

  1. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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.
     
  2. jim mills

    jim mills New Member

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    What the hell is kerdi-koll. I thought they simply recomended using a non modified mortar with a 2" overlap to create a water tight seal?!?!
     
  3. eurob

    eurob master tile and stone installer

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  4. eurob

    eurob master tile and stone installer

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  5. DonL

    DonL Jack of all trades Master of one

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    Videos like the one above can cause Cooties on a V-Board Forum and a users computer, and should be avoided. It also slows the site down.

    A simple Link will work just fine.


    Just saying...
     
  6. eurob

    eurob master tile and stone installer

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    You mean like this......

     
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  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    I think a lot of this comes down to expectations...

    In a conventional shower, one expects that some moisture will get through the cbu walls - not liquid, but moisture...we protect the vulnerable parts behind it with a vapor barrier (often plastic film or roofing felt).

    In a conventional shower, one expects the setting bed to get wet, and we provide a path for moisture to get out and use a material that won't be harmed by being wet (the mortar). We rely on using a waterproof liner and sealing it properly to the drain and where it was cut to cover the curb.

    We expect what's underneath the pan won't be harmed because of the waterproof pan.

    In a shower built with Kerdi, one expects that NO moisture will get beyond the waterproofing layer on either the walls or the pan. So, we expect it to successfully keep whatever is behind it perfectly dry.

    When the plumbing is installed in the house, we expect that it won't leak through the wall or ceiling onto our nice flat screen TV, or our photo book, or our artwork, or nice wooden floors or damage our walls. We also expect the same thing from our roof, windows, and doors and do not use any other protection for the drywall or objects in the rest of the house.

    All of the water that feeds the shower goes through those pipes on their way there, and often, much of the water that supplies other things in the home...all of those are feed with those pipes in the walls, ceilings, and floors, often with a second story beneath them...we do not expect those to leak.

    Why do we expect the pipes in a shower to leak and wet your substrate for your waterproofing? If you build your shower properly, neither the walls nor the floor will leak, so why obsess on what is behind or underneath them? If you're so worried about those, what about the stuff in the rest of the house...those pipes run by, over, and underneath them, too?
     
  8. eurob

    eurob master tile and stone installer

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    We limit our protection to the tiled area -- especially showers , steam showers etc. -- , drywall behind it .... is not an option .

    If you build your shower properly ....you definitely need to be obsessed with what is behind and underneath them.
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Then, you do not trust that Kerdi can actually do what it says it can...provide a waterproof layer. If it failed on the floor, the subflooring would rot out and likely the studwalls around it. If it leaks on the walls (MUCH harder to do with gravity moving it down), then, and only then, would it be an issue. But, if it works for the pan, why wouldn't it work for the walls? A properly built Kerdi shower just does not leak.
     
  10. eurob

    eurob master tile and stone installer

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    Kerdi is or was not -- ever -- in question . Drywall is . It is amazing that the drywall is the main product which holds the Kerdi and the tile . If something happen to it -- drywall -- then you can kiss goodbye the tile and the containment . Should I mention that drywall is the weakest possible material as a substrate ?

    Porcelain tile --- 2.50$/sf and up

    Kerdi ---------- 1.60$/sf and up

    Durock or
    Permabase ----- 1.30$/sf and up


    Drywall -------- 0.47$/sf ..................See where it leads us

    Protect your investment ......Kerdi is not the only item which should be considered !
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    No argument that drywall directly under tile is a bad decision where it can get wet...but, none of those examples are of a properly built Kerdi installation that failed in some manner. The point being, if you have good workmanship and follow the procedures, nothing behind the Kerdi membrane ever gets wet. If your pipe springs a leak, that's not a fault of Kerdi, and your damage if left unresolved, will likely require some tear out to access it and repair things. Modern plumbing, once installed and checked, rarely leaks, at least in the pipes...not counting the valve, but then, that leak would be on the wet side of the shower and never an issue with the integrity of the structure.
     
  12. eurob

    eurob master tile and stone installer

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    Seen this steam shower few days ago . Ready to tile the left overs from others .....no membrane present on the tray , no floor membrane tied to the walls , drain grate installed with thinset over the foam tray , unprotected foam tray from heavy miscellaneous items , air pockets under the foam tray , metal trim , etc.........this is what easy mean in real world . Just put the Kerdi over and everything else is good .......I bet they also bought the Schluter kit from a certified supplier which explained them '' how easy is to install it over the drywall '' .


    Shower&steamer screwed up.jpg
     
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    You are all pointing out what may happen if you do not follow the instructions or follow good workmanship practices...when installed properly, a Kerdi shower doesn't leak. It's not all that hard, but like most things, you need some level of skill. My neighbor calls someone in to replace a light bulb because she can't remember which way to unscrew it...some people cannot deal with even some of the little things in life. Another reason why Schluter wants you to buy their stuff from an authorized source - you have a much better likelihood of having someone who knows how to use the materials properly.

    Schluter does have lots of visual aids in the box (comes with the drain) and a handy 800-number to ask questions, and, hopefully, where you bought it has at least someone you could ask, but some people should never be trusted to build anything!
     
  14. jim mills

    jim mills New Member

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    Thank the DIY channel for 90% of the "contractors" today.
     
  15. dhagin

    dhagin builder:anti-builder

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    ... probably a few around here too. ;)
     
  16. eurob

    eurob master tile and stone installer

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    There is nothing saying the contrary. Just a messenger.......saying the same thing as Schluter's literature.
     
  17. eurob

    eurob master tile and stone installer

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    When you choose a road , you have to stick with , days in and out.

    Multiple roads need exploration , trial and error , etc. and none of the membrane mfgs are against and DO recommend proper building techniques and codes applied to it.

    The people mentioned from John's Bridge Forum have my respect and theirs posts reflect knowledge and experience. Remember one road , one direction , you have to stick with it.

    I don't see any more the point of explaining and debating . There is nothing left but copy and paste , as you are saying , and there are many which are doing it now. Seeing beyond it or reading between lines .....well , looks like it has no value , remember mediocrecy is just good enough. Or should I say Put the Kerdi on , you want leak....LOL
     
  18. eurob

    eurob master tile and stone installer

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    No more drywall talk .......Tile, stone keep them coming.
     
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    John, the reason drywall works in a shower is because when you install Kerdi properly, there is no way from that tiled side that the drywall will ever get wet. None of the examples shown by you were of a properly constructed shower or bathtub/shower when one of the approved, tested, warranted Kerdi installations were done. It is a given, that when drywall is subjected to frequent wet conditions, it does not hold up - that's all you have shown, and is generally understood by anyone with any life experience using the stuff. Pointing it out again, is like a broken record.

    If you're uncertain about which side is the wet side...look at your roof, the drywall underneath it on the ceiling and the adjacent walls - it all works fine, as does the drywall next to the windows or doors. One expects the roof, doors, windows, and shower are put together properly, and if they are, the drywall STAYS dry. The material is used because it is cost effective, and it works.

    As with anything, workmanship counts along with using the products involved as they were designed and tested. Use outside of those parameters is a wild card, and there's no guarantee it will work.

    Pathetic is trying to make yourself look good at the expense of others when they have valid opinions and reliable products and their manufacturers experience behind them. This is one of the main reasons John Whipple has been banned from several sites around the internet...and, a reason why when it comes to tiling things, the general attitude and depth of experience at www.johnbridge.com is a recommended source...you can get exposure to multiple pros without getting flak from one person.
     
  20. DougB

    DougB Member

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    @Jim DeBruycker: What IS wrong with you? Don't you have a life? Yes, yes, if you do everything perfectly as Schluter reccomends, and all the plumbing is perfect, as Schluter reccomends, then everything will be 'perfect'. Otherwise you will be im-perfect, and thus rot in hell, along with the sheetrock backer you used. And if you did use cement board - well then you are not 'pure' and may not go to Schluter Heaven.

    Your acting nuts Jim boy!!!!!

    After reading all your rants I think that maybe you should start the 'Schluter Religion' - convert as many as possible. Just as any religion, you want to convert others to your belief.

    So what? Why do I, or anyone else give a Rat's A** about your opinion. It's unreal to read your insistance about a product that you have no connection to.

    You're correct Jim - Schluter is the 'tile god' or 'shower god' or 'membrane god'. It's all good. Calm down and put your GI Joe pajamies on and get some rest.
     
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