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

John, just did a kerdi shower in my own home.

Good for you Boardable. Building your own shower is a great milestone in your 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.

What did you read about the Kerdi Board?

Water tested a piece and it seems to be fin even when exposing the raw edge to water.

Exposing the raw edge of water will soften the "Reinforcing Layer" (looks like press cardboard MDF) and allow water to wick through this layer. This will weaken the board by about 30% - 50% by my test results.


Thank god it is a stud wall so hopefully the screws will hold it in.

You did use the special Kerdi Screws and Washer System right to install the Kerdi Board? Regular screws will not cut it!!!

I used kerdi fix and applied it to all the seams that will or could leak on the kerdi for the flood test.

Did you do the shower floor and walls? Did you Kerdi Band all the screw heads and every seam?

I went with a very generous 3-8 inches of overlap so that I could be really sure of sealing.

Sealing Kerdi is a touchy thing. It needs to be perfect to work. 3-8 inches is a lot. How much of that was no-modifed thin set and how much was Kerdi Fix? I have been complaining for years about this seaming system using just non-modified thin set to seam these sheets. When I installed Kerdi I always hit the seams with Red Guard. That was a decade a go when we started. Since then my approach has improved and uses many different products to built what specific showers my clients need.

It has always bothered me that Kerdi is installed different in Europe. In Europe they seam the product with a cementious waterproofing product much like Ardex's 8+9. I have never been exposed to these products until about a few weeks back and really like what I'm seeing. To understand the difference you need to watch both the North American installation video and the European installation video. When you see the installer mix the Kerdi Col this is like Ardex's 8+9


I am reading this post and just not sure If you like Kerdi or not.

This thread is about flood testing Kerdi - Your water level should not drop over 72 hours of flood testing. You need to measure for evaporation and plug the drain so that it's connection to the vertical portion of plumbing pipe above the P-Trap is tested as well. I like Kerdi. Love Kerdi Band. Kerdi-Fix is my favourite waterproofing product but - I hate Kerdi Board and seaming Kerdi with non-modified thin-set. I hate that people say Kerdi is Hydrophobic, because it's not. And I feel the lower quality setting materials contribute to effloresence in a shower floor - causing the grout to go white or lighten up.


If the pan passes the flood test I am going to redguard the seams just for extra peace of mind and lay the tile.

Skip the Red Guard. By a small unit of Ardex 8+9 and give the entire shower floor a coat. Use a little on the wall seams and save enough to coat the floor out twice before tiling. Ardex's thin-sets are pretty amazing as well. We are using X32 for a bathtub project and love the stuff. Pretty quick setting (we are mixing a bag in six lifts to keep it creamy).

I am not researching into Wedi and it looks like a great product.

This product is on my short list to try as well. I have been trying to secure training for months with no success. I'm still waiting for the next Vancouver session.

I have built many bath surrounds with CB and even shower stalls using the vapor barrier method and never had a problem.

We see so many that hold up like champs. Mostly the nasty business is in the shower pan or when drywall is used in the shower. Cement Backer Board and Poly are field proven successful methods. That said a topical system is superior in my opinion.


I wanted to try a totaly waterproof shower so that is why I tried kerdi. Not sure how the outcome will be.

If you flood tested and installed the product with care you will be fine. If you want added protection then use Ardex 8+9 as a safety net. You can double your five year Kerdi Warranty if you use the Ardex system. Maybe call the rep and ask if you can still get it if you use their X5, X32 setting materials and their grout.

Tha major question is : Do you like kerdi or not?

Yes I do. Again - I like Kerdi, Kerdi Band and Kerdi Fix.

I do not like non-modifed thin-set as a seaming product. Think about it - Noble Company advise against this process for their membrane. Noble Company uses a product called Noble Sealant 150 (regular or low VOC) to seam their membranes. This makes a waterproof connection that still offers up some flexibility. I've used it and love it. Sometimes a shower floor's pitch is tighter and a sheet membrane just doesn't want to sit down so flat (try pushing a sheet of paper into a soup bowl - it crinkles). A liquid membrane is much easier to install here. Liquid membranes are tricky to apply perfect and coverage rates need to be followed. I'm finding on hot days liquids are not the best approach as they are drying to quick.

Being introduced to Ardex's 8+9 and X32 has been an eye opener. Finally a setting material company that embraces Schluter and goes as far as to double the warranty. Now in my shower kit I can get the best of both worlds. Kerdi as a reinforcing fabric in my corners. Kerdi Fix - my favourite shower waterproofing product. All the prefab corners inside and out. Just seamed with 8+9 (how it's done in Germany). And the kicker.

YOU CAN FLOOD TEST THE NEXT DAY !!! or in as little as 4-6 hours (yet to be proven or tested by me)

And am I better off next time laying up CB and painting on liquid redguard and using a wedi preformed pan?

Depends on the project. Lets look at that when it comes up.


or a Kerdi pan and drain and CB and redguard.

Kerdi system only - 5 year warranty
Kerdi and Red Guard Hybrid - No warranty
Kerdi and Ardex 8+9 system - 10 year warranty.

Red Guard is like $65.00 here in Vancouver for a small bucket (70 square feet). Ardex 8+9 is $100.00

For $35.00 more you can go from having no warranty to a ten year one. You need to use their grout and X32 or X5 thinset I believe. Email this guy - he can send you your local Ardex rep's name and number : Robert Russell < Robert.Russell@ArdexAmericas.com >

Just looking for your ultimate bullet proof shower recipe and Opinion on whether I just made the biggest mistake of my life with Kerdi ?

Relax!!! You checked your work with a flood test. Your golden. Protect the shower floor or set it first.

Good Luck with the tiling!

JW

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.

Ardex stuff is generally available, but not at a big box store... http://www.ardex.com/productDetail.a...tentParentID=2.

To locate the ARDEX Americas Sales Professional for your area, please call 1-888-512-7339 or email your request to info@ardexamericas.com.

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.

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.

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?

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.

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.

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.

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

Ardex is right now building a 20 million dollar plant in California! Or so I'm told.

Email Robert Russell @ Robert.Russell@ArdexAmericas.com He'll find your local rep and let you know where you can buy the 8+9.

Nice work on the flood test.

Do you have an evaporation control in place?

JW

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Originally Posted by boardable

....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

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I believe the Ardex warranty is replacement. With Red Guard you would need to have used Wonder Board and their premium thin-set. Laticrete has a 25 year warranty as well with their premium lines of products.

Before you make the next move. What thin-set will you be installing. Ask them what to do. Send them an email with a picture showing (proving) your flood test and ask if you can do A,B,C from here.

Have you prepared a tile sample board with grout? This should be the next step....

JW

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

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

A properly built shower has NO standing water...a flood test is an absolute worst case test that a real shower should never see once completed. If it didn't leak with that, there's essentially NO water pressure to push any moisture into the seams during typical use...IOW, don't worry about it! Any water in the shower will flow down the wall and along the slope to the drain. Any (very small) amount that MIGHT get below the tile, will do the same thing. There shouldn't be ANY accumulation of moisture beneath the tile of the pan with the membrane and the slope to the drain...it MIGHT get a little damp if used continuously, but no standing water enough to wick anywhere. This is the one big advantage of a surface membrane, however achieved: the water stops at that point and doesn't saturate the substrate. Now, in a conventional shower, that substrate should handle being wet, but IMHO, it's better to never give it the chance!