Schluter kerdi shower water test dark spots question/problem?

[tom1]

Hello everyone on John Bridge Forum,

I am completing my first Schluter kerdi shower and did a water test as I saw recommended on this forum. I read that water should not go ingot the shower pan piece. I noticed some discoloration in the shower pan and wanted to post here to see if this is a big problem and how to correct it if it is. I will post the pictueres in this thread also. I ran the water flood test for 24 hours and the water level stayed the same so there was no leaking. Any reply would be very much appreciated as I am unsure if this result is acceptable.

Thanks,

Tom

[jgleason]

Hi Tom,

Looks like a good bit of wicking there. Very neat seams, maybe too neat. Tell us about the thinset you used, how you mixed it and its consistency. Size trowel used?

[tom1]

Hi jgleason,

Thanks for your quick reply. I used flextile (brand) unmodified white and I mixed it to a medium thickness consistency. When I was applying it , the temperature was very warm. The trowel I used was a 3/16 v-notch.

Thanks,

Tom

[jgleason]

Also...how did you get your 2" overlaps? From the pics it is hard to tell if you used KerdiBand maybe first then laid the shower floor piece of Kerdi on top? Every seam needs a 2" overlap. The corner pieces at each point of your shower would look like this...


And if you installed KerdiBand first it might look something like this before finishing the rest of the Kerdi...

[jgleason]

I haven't used the Flextile brand but if you mean their Flextile 53 product it looks comparable to Laticrete 317 on portland cement content.

How long after installing Kerdi did you wait before starting the flood test?

[tom1]

I used kerdi band exactly as you described, I put the kerdi band on the bottom corners first and then put the shower pan piece above it. There is a 2" overlap.

Good thing I took a pic of this, I will attach it here and it shows the band put in before the top shower pan piece.

[tom1]

I waited probably 2 months before I water tested. Does this look like a huge problem? do you think I am going to have to rip a piece out or is there another way to fix it?

[jgleason]

Ok, I think that is your problem. No issue with Kerdi Band first then Kerdi BUT the foam tray should have been installed first then KerdiBand. As it is your tray sits on top of the bottom edge of the KerdiBsand which is thinsetted to the flat floor. When you installed the Kerdi on top of the tray that is where you need the 2" overlap.

So if I understood you correctly and from your latest picture, the top image in my crude drawing is what you currently have and the bottom of my drawing is what you need to do to fix it...


Ugh...picture not big enough. These should be zoomed in enough...

[tom1]

Sorry jgleason, I dont think the pic is the greatest at showing my installation. I installed the foam first, then the kerdi band in the pic is on top of the foam, then I installed the walls, and then I installed the floor. I watched the video and instructions on the Schluter site. I had purchased the kit with the tray, and it came with the instructions in it and I followed those along with the vides on the site. In the pic, I was using a piece of the foam that I trimmed as it was a custom showe pan size to put a stool on to rach the ceiling as I didnt want to damage the foam shower pan installed under it. There is a bit of cement over the kerdi band which I cleaned off before putting on the floor pice over the foam shower pan.

[tom1]

So my installation is like the one in the bottom portion of the pic you sent, except the kerdi band is under the walls and floor section.

Thanks,

Tom

[jgleason]

Ok Tom. It was hard to tell from your pic whether the foam tray was installed first then teh band. Looks correct. The wicking looks like it goes beyond the 2 inch overlap in several places. Unusual maybe but the amount of water that gets underneath the tile and grout doesn't bring the same pressure on the seams as standing water in the pan without tile. I don't think you have much to worry about, if anything. Wait for a few of the pros to chime in to confirm we haven't missed anything.

[jadnashua]

Your thinset may have been mixed a bit dry. It should be creamy enough so that it holds a notch, but just barely. SOrt of like mayonnaise, not peanut butter. Did you pull any of the sheets part way off to verify the full coverage? This is important verification test to see if you've got the right mix and technique. Once you've got it, you don't have to do it again until you mix a new batch of thinset up.

Keep in mind that the flood test is probably the first and last time there will be long-term standing water in the pan. But, when you've mixed the thinset properly and embedded the sheets well, it typically only penetrates about 1/4" or so. Can you still see any of the notches through the Kerdi? WHen dry, it should look pretty consistent color, and you should not be able to see uncompressed notches (which would indicate the thinset was too dry, had skinned over, or you didn't press it into the thinset).

[tom1]

Thanks jgleason, good to hear it won't have the same pressure, will see what everybody has to say.

Hi jadnashua, maybe it was mixed too dry or do you hink it is possible the thinset was drying too quick? It was hot in the room when I was applying it. I did lift it a bit when I was putting it on and it looked like it was applying to both sides. Is it possible that maybe I put too much pressure on it and maybe ended up making it thinner on the parts closest the edges?

I do not see any notches through the kerdi at all, the color when dry was consistent throughout. Do you think this will cause a problem the way it is?

Thanks,

Tom

[jadnashua]

One thing that makes a big difference, even when the thinset is mixed properly, is to wipe the walls down well with a wet sponge first before applying the thinset. It really makes a difference. Some people compensate by mixing the thinset thinner, but that affects the overall strength. Wiping the walls first does two things, removes any dust, and means that the thinset you apply won't get the moisture sucked out of it.

I think things will be fine, but it won't hurt to call Schluter on their help line - they're quite good about knowing their product and diagnosing things.

The way that the Kerdi membrane stops moisture flow is by disrupting the capillary action with the fleece. If the layers are further apart than they should be, the thinset itself can wick. This can happen if things dry out too fast (thus the reason to wipe the walls down first). Tried this at one of their classes, and it was surprising the difference! You shouldn't have a problem since as long as the pan is sloped properly, there won't be any liquid water under there.

[Topspin]

Well after 2 months one thing is for certain, your not in a hurry for a shower. So take time to call Schluter tech support, then if they say all is ok, for belts and suspenders - you could apply Kerdi Fix on the seams. Ain't nothin gettin past that barrier.

When I find a corner burp the next day, or just want to really seal up the drain flange ring, I coat the seam with K-Fix and sleep well at night.