How much should the water level drop in a Kerdi Shower flood test?

Discussion in 'Shower & bathtub Forum & Blog' started by johnfrwhipple, Dec 25, 2011.

  1. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.

    What is a Capillary Break?

    Here is a hint....

    [​IMG]

    This shower was flood test for three plus days. No water level drop. No Capillary action causing leaking over the dam. Why?


    The blue membrane in the photo is not Kerdi. It is called NobleSeal TS. Sold by Noble Company and available across the US and in limited areas in Canada.... NobleSeal TS cab be affected to a primary shower drain (clamping drain shown in photo) and has one of the best perm ratings of any sheet membrane sold world wide. Perfect for your ACO shower drain installations. Perfect for a residential shower. Steam shower and perfectly suited for a high use commercial steam shower setting as well.

    Not all shower sheet membranes are created equal - do your homework.
    Last edited: May 16, 2014
  2. pitterpat

    pitterpat HandyWOMAN

    Messages:
    46
    Location:
    Indianapolis
    Hi,

    The Schluter rep will typically say just the evaporation amount.

    Pat
  3. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    Weep holes and clamping drains are part and parcel to a conventional shower construction, and the gravity and draining on that was what was said. Except during a flood test, a shower NEVER should see pooled, liquid water on the membrane ever again (except possibly in a conventional shower's liner). The tile and grout will wick some, but because there's not a huge, thick, absorbant mudbed beneath, it dries to the surface quickly once you stop showering.

    If you take some virgin Kerdi and sprinkle some water on it, it will bead up. Eventually, it will go into the fleece. Your picture does not appear to be of a shower, but some mock up and the Kerdi is not well adhered to the backing material. Initially, the water will bead up similar to a bead of water on a nicely waxed car, eventually, it will wet the surface and then the meniscus will invert. Water will wick a little into a seam, the more thinset you leave there, the further it will wick. If your seams overlap at least the minimum specified, it will not get beyond the seam into the backing material. That is the goal, and if done right will make a perfectly waterproof shower as once the tile is installed, very little water will ever get to the membrane and certainly not enough to pool long enough to do anything. That is the beauty of ANY surface membrane.

    Once the fleece does get wetted, it also acts like the pad of a humdifier, and can significantly increase the amount of water lost to evaporation during any extended leak test. The small fibers significantly increase the surface area and lots more water will evaporate from that larger surface area. Just like in an evaporative cooler or a home humidifier.
    Last edited: Dec 26, 2011
  5. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  6. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    All the chatter makes me want to avoid a membrane that isn't liquid... The more I read the more I don't like what I see.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    The stuff works as a system, your Kerdi is not adhered to the surface properly, nor is that an approved corner, nor do you have the required overlap and there's too much thinset, where it is used, allowing the thinset to absorb moisture. If the stuff is anchored properly as if it was a real shower, you'd see different results - just like you would in a properly constructed shower. A proper seam has at least two inches of membrane overlap with a thin layer of thinset well embedded into the fleece. Mock it up as if it was a real shower pan, and you'd see different results...I know, as I've seen it. Days of being full of water and no evidence of moisture intrusion.
  8. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  9. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    Using too much, or too dry of a thinset layer underneath any sheet membrane, especially at the seams is probably the biggest error people make. Using the proper mixing, trowel, and the proper angle and this normally isn't an issue at all. A properly mixed thinset for this application can hold a notch, but just barely and a bit of slump may be better than nice crisp notches. If you embed the fleece properly, and you should pull back a section while doing this to check, then it will not wick past the mandated minimum 2" seam. The instructions say to wait at least 24-hours after installation of Kerdi prior to performing a flood test. Then, if you use a modified thinset, it may never perform properly. It all comes back to workmanship and following the instructions.

    As I've said before, overnight, and especially over several days, in the winter particularly or if you happen to live in the dry southwest of the US, an 1/8" per day or more is not unheard of for the level to drop in a waterproof container, let alone one with fabric mesh on it that can wick a bit of moisture up into the air and significantly increase the surface area. My toilets will drop over an inch a week with the lid down while away on vacation...with the area totally open like in a shower stall...I'd not be surprised if it was more. Living in a temperate rain forrest is not the norm for most people...your results may differ. The RH in my place right now is 23%. Vancouver is likely much higher than that most seasons.

    Then, you have to consider that except during a flood test, a shower will likely never again have standing water in it. Even a poorly installed one still takes a long time for the water to wick into an improper seam - far longer than a typical cbu would take to wick up from the liner far enough to cause damage there. From a test someone did, they found that cbu tends to wick up about 6" when sitting in liquid water which might happen in an improperly installed conventional shower with a waterlogged pan. This is likely cbu brand dependent, as some wick more than others.
  11. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Is Kerdi Hydrophobic? I say no. How can a material that wicks water be Hydrophobic

    Posts removed by John Whipple
    Last edited: Mar 15, 2014
  12. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Failed Kerdi Board Hydro Ban Niche Detail.

    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  13. Justadrip

    Justadrip New Member

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    66
    Location:
    New York
    ...because no one cares about it.
  14. boardable

    boardable New Member

    Messages:
    51
    Location:
    San Jose, Ca
    John, just did a kerdi shower in my own home. Used Kerdi board and kerdi styrofoam pan with membrane and kerdi drain. Of course after the board is all in, niches cut and sealed I read about the kerdi baord. Water tested a piece and it seems to be fin even when exposing the raw edge to water. Thank god it is a stud wall so hopefully the screws will hold it in. I used kerdi fix and applied it to all the seams that will or could leak on the kerdi for the flood test. I went with a very generous 3-8 inches of overlap so that I could be really sure of sealing. I am reading this post and just not sure If you like Kerdi or not. If the pan passes the flood test I am going to redguard the seams just for extra peace of mind and lay the tile. I am not researching into Wedi and it looks like a great product. I have built many bath surrounds with CB and even shower stalls using the vapor barrier method and never had a problem. I wanted to try a totaly waterproof shower so that is why I tried kerdi. Not sure how the outcome will be. Tha major question is : Do you like kerdi or not? And am I better off next time laying up CB and painting on liquid redguard and using a wedi preformed pan? or a Kerdi pan and drain and CB and redguard. Just looking for your ultimate bullet proof shower recipe and Opinion on whether I just made the biggest mistake of my life with Kerdi ?
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    Kerdi has been used for MANY years...if it regularly failed, you'd hear about it. As with anything you piece together, it all comes down to the workmanship. If you do it right (assuming it's a good product, and Kerdi is), it will last. Now, you could argue there may be better products. Just like there are lots of choices in life, what's best for one may not be the best for another. there are pros and cons to anything.

    The only failures I've heard of with Kerdiboard are where they either were placed where there was excessive heat (uninsulated steam pipe) or the edge was not sealed at a joint properly, or the cutting technique delaminated it from the foam (as I understand it, that was a defective batch that was recalled and the process resolved - that was several years ago just after it was introduced).
  16. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,782
    Location:
    North Vancouver, BC
    Kerdi Shower flood test - Red Guard or Ardex 8+9 as extra insurance

    Posts removed by John Whipple

    Sorry Folks - I have taken down my post on Schluter's products. Just being careful with my wording.

    There is very little info online on the subject of flood testing a Kerdi shower. I have used Kerdi now on many shower builds and have so for years (about 13). I follow the European installation protocol and over the last 16 months flooded many Kerdi showers. None dropped in level at all. Not a 1/8".

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking. To learn how to do this call Schluter or call me. My number is below. I have documented the process over and over and have dozens of detailed photo's showing the measures I take so you do not fail this oh so important step.
    Last edited: Apr 27, 2014
  17. boardable

    boardable New Member

    Messages:
    51
    Location:
    San Jose, Ca
    John, Of course I used the Kerdi screws and washers. Made patches big enough to cover 2 inches on ever side of the washer/screw combo. Unmodified thinset as required. Banded well over the required 2". Not being very clean with my kerdi install of course there was a lot of exposed thinset. So the next day I used a damp sponge and water and cleaned up the surface thinset. Noticed I got a defective ( old delaminated kerdi band) batch of kerdi band so ripped off the two pieces I made off of that band. Cleaned the thinset off and went in with a new roll of good kerdi band. I don't know how people clean the kerdi band when the thinset is wet ( still a mess). Used kerdi fix just on the outside surface of the seams like a caulk almost. I have a neo angled shower so I had to use it on the two 45 degree corners (why kerdi does'nt make a 45 degree corner I have no idea. Tested my plug the other day and it leaked or the water evaporated. I am going to say evaporated because I made a tiny kerdi tub and put water in it to test the waterproof membrane just for fun and that was all evaporated in less than a day also. Removed the plug and made sure nothing was stopping my seal. Once again I am just using the small red test plug with wing nut on top. tested it for a hour and no water drop. Commenced flood testing. stacked coins (Its a crap load of coins). It wicked higher than I would have liked but it seems it is only where there is thinset left on the membrane. I can see spots that I did not touch that look like dry membrane under water and then I can see spots where I set my water bucket on the membrane to clean the other day. You can actually see the imprint of the bottom of the bucket. I can see the drain flange but could see that before so no surpise ( yes I used kerdi fix to seal the lip around the drain also) Wicking in the sides some wicks none and some up to the top of the curb then stops. Over a 12 hour period I got a water drop of half a pennies width. Probably evaporation or the drain plug leaking a little over that time. Topped it off with about 14 oz of water and we will see what happens next. I plan on leaving the test for probably 72 hours. Also luckily the rest of the bathroom floor isnt sealed so I can crawl under and inspect for leaks. Since I did quiet a bit of scrubbing on the membrane ( nothing that messed anything up) and water has been on it before I'm not concerned with the discoloring as I know it isn't water getting under. The wicking happened even with the damp rag and water I spilled while washing away excessive thinset. Just wondering your thoughts? And Ardex here in california would be almost impossible to get.
    Last edited: Sep 28, 2012
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
  19. boardable

    boardable New Member

    Messages:
    51
    Location:
    San Jose, Ca
    Jim, the only way I am getting ARDEX is if I drive about 10 hours north or ten hours south. The way I see it is a warranty on a product isn't worth anything because you still have to tear it out and all they are going to do is give you more product. You still have to do all the labor.
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    I'm surprised to hear you can't get it anywhere closer, but it is what it is. If things pass the flood test, and you don't damage things in the process of applying tile, it should be fine. Just cover things while standing in there until you get to the tile on the floor. You want it tough enough so if you drop a trowel , step on something, or who knows what, you don't poke a hole in things.
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