water level drop

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

  1. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD for both Canada & the US

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    There is very little info online on the subject of flood testing showers.

    Your key steps is measuring the water level exactly and ensuring you get no capillary wicking.

    What is a Capillary Break?

    Here is a hint....

    This shower was flood test for three plus days. No water level drop. No Capillary action causing leaking over the dam. Why?
     
    Last edited by a moderator: Nov 23, 2016
  2. pitterpat

    pitterpat HandyWOMAN

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    Hi,

    The Schluter rep will typically say just the evaporation amount.

    Pat
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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. dlarrivee

    dlarrivee New Member

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    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.
     
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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.
     
  8. Justadrip

    Justadrip Member

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    ...because no one cares about it.
     
  9. boardable

    boardable New Member

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    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 ?
     
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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).
     
  11. boardable

    boardable New Member

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    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
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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  13. boardable

    boardable New Member

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    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.
     
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    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.
     
  15. boardable

    boardable New Member

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    I think I may be laying tile backwards. Because I am doing this in my own house I lay the shower floor tile first. Wait a day or two ( preferable two) . Then throw down some thick towels and a cardboard box and work my way up the wall. I like to do this to make sure the lower tiles are of full size. The little tile cuts can stay at the top. If I was doing this job for a customer I would do the wall tile then make my pan. For this job I do it this way. Once again kind of a novice so experience is teaching me. As far as my wet test I am a bit concerned about the coloring of the kerdi membrane and the wicking. Is this normal? just because of my scrubbing of the thinset off of the kerdi before?
     
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A proper joint won't wick more than around 1/4" under pressure. The recommended overlap is at least 2", which is 8x normal to account for minor deviations in perfect. If your flood test was good, you're fine.

    Nothing wrong with doing the floor first as long as you protect it well. Your layout should avoid slivers, either at the top or the bottom, so adjust the layout to avoid that which may mean partial tiles both top and bottom.
     
  17. boardable

    boardable New Member

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    Jim definately. Looks so lame with little slivers I would rather half two tiles and make them a little less than a half etc or use the grout line to make it up than do a quarter tile. It looks like the water is just wicking up the thinset on the top of the membrane not under. But it is weird that I can see the bucket marks where I set the bucket down. May have compressed the fleece who knows. I'm using a foam pan liner so any leak will show quick since it has no where to go.
     
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A full bucket of water has a significant pressure on the narrow rim, and could easily squish most of the thinset out and leave a depression. Not a big deal. Next time, set it on a piece of ply or something , to distribute the weight.
     
  19. boardable

    boardable New Member

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    24hours no drop. But my joint did wick up over 4 inches. There is no way it isn't seamed correctly. I used kerdi corners and the piece is one piece. I ran it up the wall. I guess it just runs up the thinset. Crawled under the house and inspected. No leaks anywhere. Before I layed the floor I put down self leveling compound to level the floor then put the pan down. The only place for water to go would be the wall ( which I can see) or around the hole in the floor for the drain. Nothin there. I'm calling it good and for piece of mind all the seems are getting the redgard insurance. I have a left over bucket from my dads shower i did a month ago. For you pros, does the warranty extend to paying for labor if the product fails. If not who cares. Spending 300 dollars for more membrane when it fails isn't as bad as doing free work. Would rather just use the liquid on every seam and be over it
     
  20. boardable

    boardable New Member

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    John I have no prepared a tile sample board. What is that. No evap control. My pan wicked the same as your test box. Very disturbing. how can I make sure no water is just sitting below the membrane in some way. Even if it is just a little ? Only way I can think of is to cut a price of the krdi out and see hen make a patch to cover. Really wouldn't like to do it. But using gray thinset didn't halp in making it easy to see. Would it be almost black looking through the membrane ? Because it was dark just from me pressing when squeezing out thinset and when I was cleaning with water
     
  21. boardable

    boardable New Member

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    Please excuse the horrible
    Spelling. iPhone is not a great device to do speedy typing on
     
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