Kerdi 7 Day Flood Test

[916tile]

Not sure if you all are aware of how Kerdi functions over long submersion. This is the 5th test in a series. Lightweight thinset has higher rate of absorption. I see you guys are sponsored by Schluter. So take down if needed.
https://youtu.be/1Q4KFJrOMxI

[Topspin]

Well isn’t that something.

[mullet]

7 Days? With modified? hmmm I asked the same thing in my shower thread about the wicking. LOL I wonder why you don't use Kerdi as a liner for a traditional shower pan. I will never use my shower as a tub.

[cx]

Looks to me as though your early comments in the video were maybe accurate, Isaac, that it's the "lightweight" mortar that might be making the difference there.

We've seen cardboard boxes lined with Kerdi membrane and filled with water that have soaked for years without leaking. One was used at the CTEF Schluter seminars as an ice bucket for years without a problem.

And those were made without the pre-formed corners, even.

[916tile]

Out of 3 tests I've done, using both unmodified and ardex, I had similar results over 7 days. The 2 Ardex tests I did were way worse than the Laticrete 317. I have heard the cardboard box thing. I have yet to try it, but cannot fathom how it would work unless the box being able to breathe would dry the thinset before it could saturate the box.
I've been doing these tests for about 5 months. It all started with a cut and fold corner 24 hr test. When I saw water had absorbed between the sheets almost a 1/2" in 24 hrs, it got this whole thing going. I started doing longer tests and it seems to be that after 4 days, the absorption will move the full 2", into the substrate.
It is a very slow rate, and Kerdi is not meant to be submerged. So these tests are for information only, as most people believe it to be 100% waterproof. A shower is usually dried out before each use so even though the seams are not waterproof, it still works.

[Just In Tile LLC]

I'm glad you brought up the test does over stress the product to a point of failure Isaac.

I used a metal prefab niche' one time that has the sand epoxied into it. Since it was my first time using one I flood tested it over night before I used it. Water was gone the next day. Called the company and they said it will never see that amount of water in that way.


After discussing with the homeowner the answer received, I siliconed the metal folds in the corners and retested. No leaks, we both agreed no water leaking is better than some water leaking even if it was "overstressed" by my test.


I since continue to build my own niches with self adhere flashing under my mud, I doubt they hold water like that prefab niche if I flood tested them, but...they'll never see that type of water in that way.

[speed51133]

well, how many days of no leaking is considered passing the test??

I guess my schluter kerdi swimming pool with gypsum walls was a bad idea???

[Just In Tile LLC]

I'd say one day less than when the leaks start Mike but yes your swimming pool was a bad idea.

In all seriousness I'm all for building it the best way, even if it's slightly overkill. I've never tested my flashed niches this way, but I should. They might actually hold water like a tub the way I do them.

[ss3964spd]

Maybe I wasn't seeing it right, but it appears that the bands were not over lapped and mortared to the bottom, though the pre-formed corners were.

[Dave Gobis]

I was the keeper and filler of the "box" and it did indeed last years even after a bleach attempt to kill the surface tension. Its demise was caused by a fatal pocket knife stab inflicted by an unknown scum of the earth attendee.

[916tile]

Everything was overlapped minumum of 2". If you click one of the the links in the description of the video, you will see the very detailed build episode showing step by step construction.
Yes, I agree this "test" is overkill and way more water than should be in a shower. But I was just showing how it functions. Most of us have not understood correctly how kerdi works. I installed it for 5 years, telling customers that is 100% waterproof, that you could fill it up for 100 years and the most the moisture could penetrate was 1/4" under the band.

[mullet]

I believe this is the best explanation.

https://www.johnbridge.com/vbulletin...d.php?t=112023

Originally Posted by Jim DeBruycker

There is a reason why they specify a 2" overlap on the seams...plus, consider that the mortar will continue to cure for a long time - keep in mind that its strength is specified after 28-days, and in reality, it continues to cure for years. When cement cures, it grows spire like crystals and ends up being interlocking, gaining strength and water tightness.

The worst time in any shower (especially a surface membrane where the mud bed won't become saturated) is during a flood test. In a Kerdi shower, once the tile is on and the grout is installed, with very little beneath the tile, there is just no standing water pressure to drive water into the seams.

You should be fine.

If you were to do this again, as CX said, put a control pan of water outside of the shower so you can compare the levels - evaporation over three days, could be significant. That isn't usually a big deal if you do a more normal 24-hour flood test, but still could be if you were in the summer in the desert!

[ss3964spd]

Still not seeing it Isaac, maybe it's just me, but at the 4 minute mark in the video, when you start removing the side band, it sure does not appear to be a 2" overlap onto the base.

[mullet]

Its overlapped, they put the corners down first then the 4" band down, then the bottom, then the sides. I wouldn't say the overlaps are tight joints, they left a lot of the thinset in the overlaps, like an oreo cookie LOL, IMO.

[RichVT]

It looked like a lot of thinset in the overlaps to me when I watched. Could very well be the problem.