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

    Messages:
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    Location:
    New England
    If you think this way, why don't you use it on the ceiling in case your roof leaks, or around your windows and doors? Installed properly, it works. Nothing says you can't use the other materials, but, if it DID leak, eventually, you'd still have to tear out and fix it.

    I have no problem if you wish to use any of the approved materials, it's just that I do object to the jerk reaction that it WILL fail if you use drywall there after it has been tested and proven, done properly, it doesn't matter.

    I think we can both agree that drywall is quicker and easier to put up than cbu, and costs less. It works. The choice is yours, just don't tell me it won't work and will fail, because that has never been proven or demonstrated when installed properly. And, having done it, it really isn't all that hard to do properly. Pretty simple rules, ensure proper coverage by periodically pulling back the membrane to verify coverage, and make all of your seams at least a 2" overlap...anyone attempting to build a shower should be able to handle that. If not, pay someone to do it for you.
  2. DougB

    DougB Member

    Because your ceilings and walls are not subjected to gallons and gallons of water every day.

    Well they sell 108 sq/ft of Kerdi for $164. Then you need corners and tape and pipe seals and mixing valve seal. Then too, you have the thin set cost.

    Here's what one fellow worte. Bought it, ... called Schluter for a couple of questions relating to steam shower application...and guess what! All warranties are OFF (as in null and void) when purchased online.

    What a scam!
    Last edited by a moderator: Jan 28, 2014
  3. loudgonzo

    loudgonzo New Member

    Messages:
    25
    Location:
    Wylie, Tx
    Here's a wider picture of our bath, the stand in shower on the left will be torn out and converted to a storage closet after the walk in shower is completed on the right side. The shower valve and head will be mounted on the wall that is dividing the shower and alcove right now.

    My reason for using hardi instead of sheetrock is based on the following "what if"; If a leak develops around the valve or along the plumbing on that divider wall, the soon to be closet wall can be torn down and the leak fixed, the hardi is more resistant to water damage and can prevent tear down of shower tile, since we would be able to access it from the back in this case, where if the drywall were to get wet from a leak, it would have to be replaced requiring total tear down?

    Is my assumption above correct, or am I overlooking something? In short, I can rely on waterproofing the exposed side, but will hardi be better than drywall in this scenario?

    thanks
    Leo

    photo (28).jpg
  4. Vegas_sparky

    Vegas_sparky Digital Billy

    Messages:
    382
    Location:
    LV,NV/ Nowhere,UT
    I used Hardi on all the wet side walls of my shower. Green board is on the dry side of the same walls. I covered the Hardi with Regard, so mines still shit anyways.

    Can someone pass me the popcorn please?
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,273
    Location:
    New England
    It's not like they don't tell you this upfront - IF you look at the company's website, it's right there on the first page. The reason for an authorized dealer is that you have a chance of someone there being able to guide you in the proper use of the material...just like when you buy a grey market item (a camera, watch, etc.) the company, I don't care if it is Nikon, Cannon, Rolex, etc...they will not warranty the item.
    Last edited by a moderator: Jan 28, 2014
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,273
    Location:
    New England
    The only company that has a tested and approved method of building a shower with drywall as the substrate is Schluter with Kerdi. NO other methods have been tested and approved. Depending on how long and how big a leak that might occur, neither Hardie nor drywall may be enough...the underlying wood would rot out. Drywall doesn't immediately fail, you have to soak it. If there's enough to soak it, your structure is at risk.

    How many people build their house to be tolerant of a pipe leak? Nobody. Think of all of the water pipes in the walls and ceilings, beneath kitchen and bathroom sinks, toilets, etc. You test that as well before you close it up and you don't waterproof the walls and ceiling around where they run, either.

    If you cannot tolerate the possibility that something could break, build it a different way and protect yourself...but, a properly built Kerdi shower does not leak, now, or in the future. Any shower, improperly built can lead to structure damage and necessitate a tearout and rebuild.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,273
    Location:
    New England
    Custom Building Products has specific instructions on how to use RedGard as a waterproofing layer in a shower. If you follow their instructions carefully and have good workmanship, it can work. Personally, I prefer a sheet membrane. RedGard applied too thin or too thick or with a pinhole is less than ideal.
  8. DougB

    DougB Member

    Hey man - it's not a camera, not a car, it's some damn fabric that comes off a roller in a factory.

    So I'm supposed to go to a web site? A warranty is a warranty. If it's installed wrong, then it's on me.

    However, if I have installed the product many times, I still have to buy it from an autorized dealer to get the warranty? - which I assume nobody has ever met their spec - thus they have yet to pay a single claim. The only way for the product to fail is if the material is deffective.

    It's a scam Mr Red Sneaker!
  9. DougB

    DougB Member

    I considered it with the three showers I have built. I considered that there is a possibility that perhaps the shower arm (threaded into the drop ear ell) could leak, same for tub spout connection, or a mixing valve. Cement board won't be a problem. Also I was fortunate that I could put an access panel behind the shower valves.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,273
    Location:
    New England
    If the leak happens long enough before you notice it, you'll have wood rot, and probably damage to the ceilings below. The ceilings below will probably be the first you notice it if it doesn't leak out onto the floor of that room. And, that does not mean you'd have a failure in the wall assembly...most of it would run down to the floor, and in between, there's a chance it would evaporate...drywall sitting in water damages it faster than a bit of spray while you're actually showering.
  11. DougB

    DougB Member

    Look - I don't question the effectiveness of Kerdi. I'm sure it's a quality product.

    The rub is that there are products (like cement board) that are inherently moisture resistant - that cost very little more than drywall - which has no moisture resistance. So you sorta have an extra level of insurance - risk advoidance.

    You want to take the risk - fine. But for me, the 'ease' of drywall is not worth my percieved risk.
  12. eurob

    eurob master tile and stone installer

    Messages:
    833
    Location:
    Montreal
    Yeap. -- combined with other threads on the same subject ---> what a waste of time < ---- .
  13. dhagin

    dhagin builder:anti-builder

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    Location:
    oahu
    Regarding this site being frequented by DIYers- I agree. These days, anyone with a computer or phone can access any of this info and learn from it. Hopefully, the main thing they leave with is this:

    Always follow the local building codes & laws, and the manufacturers installation instructions with whatever product you use. If there's a conflict between any of these - and there frequently is - ask or hire a pro to sort it out for you.

    At least some of us are Pro's here and have been in business for decades. Some pro's maintain their edge through continuing education with the manufacturers, local code authorites, forums like this, etc... Most times, we can help folks sort the wheat from the chaff... but not always. The other thing folks should take away is that many here have their own opinions of things formed through direct experience over the course of many years or decades, and that each opinion may be different from others' opinions, AND valid as well. This last part is often the most difficult to grasp, yet is most important to remember. :)
  14. eurob

    eurob master tile and stone installer

    Messages:
    833
    Location:
    Montreal
    The condensed answer to the Op thread is - Kerdi is providing a reliable , efficient and constant protection against water in liquid or vapor state , regardless of the approved substrate.--

    The substrate is in question here , not Kerdi. Experience and other technical documentations say drywall is NOT to be use in a wet area.

    It is just to easy -- the word easy is like a plague -- to rely on other trades for the safety of your tiled shower or wet area and say I am protected because I installed the Kerdi.

    Properly build conditions exist only when you monitor the build constantly, which is not possible most of the time.
  15. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  16. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  17. eurob

    eurob master tile and stone installer

    Messages:
    833
    Location:
    Montreal
    I guess John , is like only looking at one mfg recommendation, without considering the other ones.

    Selling a high priced membrane over the cheapest product -- as substrate -- is the " winning " combination!:rolleyes:
  18. jim mills

    jim mills New Member

    Messages:
    141
    Location:
    nebraska
    I still beg the question: If I install Kerdi over CMU, and the shower develops a leak, what have I gained by using the CMU? I'm not necessarily on the side of using drywall, I am just curious.
  19. loudgonzo

    loudgonzo New Member

    Messages:
    25
    Location:
    Wylie, Tx
    The way I'm looking at it is if my valve leaks, and I realize this due to a puddle on the dry/opposite side of shower, I can access the leak from the back side and repair it, the hardi will have gotten wet/damp, but could still be OK after it drys, where as if the sheetrock got wet, it's more likely that it is damaged beyond repair and require complete teardown tile and all.

    leo
  20. eurob

    eurob master tile and stone installer

    Messages:
    833
    Location:
    Montreal
    No debonding or major dammage to the integrity of the assembly .

    If debonding at the connection of the membrane with the CBU happens, then there is really no point in using the membrane ! A question to be asked to Sch.Tec.Dep. if curious.

    Dammage due to a faulty valve or etc. can be more costly than the cost of the CBU-- read difference in between--.
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