Kerdi Flood Test Failure

[Tyler Morkin]

Hello everyone!

I'm new to posting on this forum, but I've read a lot of very helpful information here.

I'm in the middle of a bathroom remodel and installed a Kerdi shower using one of their box kits. It has been installed for several weeks now with no tile while I work on other areas of the bathroom (and, you know, work my full time job!). I just flood tested it last night and it has failed. There is a small amount of visible water outside of the curb and it is dripping quite a bit underneath in the crawl space. The water level went down only somewhat, so we're not dealing with anything catastrophic here.

This is where I need advice. What should my next steps be? I paid a lot of money so far for materials in this renovation, so I want it to be right. However, I don't really want to tear it all out and start over. Any advice I could get could be much appreciated.

Thanks for everyone's willingness to help.

Tyler

 

[Standardairconditioner]

Call Kerdi and they can help you minimize what you may need to tear down and replace.

Along the way, you will also learn that you did not follow Kerdi's strict install instructions down to the period.

When people mis-interpret or omit a step, this is how we get product failure from a bad install.

 

[Sponsor]

 

[Tyler Morkin]

Here's a shot of the pan after I drained the water. The water on top of the curb was from when I pulled out the plug. The water in front, however, worked its way there.

The way I see this, I have 4 options:

1) Not worry about it since the shower will never have standing water again

2) Rip it out and start over (want to avoid at all cost)

2) Place a new sheet of fleece on top and redo seams with new Kerdi band

3) Cover with Red Guard (not ever sure if you can/should do that in this case)​

 

[Tyler Morkin]

Call Kerdi and they can help you minimize what you may need to tear down and replace.

Along the way, you will also learn that you did not follow Kerdi's strict install instructions down to the period.

When people mis-interpret or omit a step, this is how we get product failure from a bad install.

I will do that right now. I had planned to do that before I posted, but I wanted to see if anyone had ideas first.

Thank you for responding.

 

[Standardairconditioner]

1) Not worry about it since the shower will never have standing water again

Worry.

2) Rip it out and start over (want to avoid at all cost)

Schluter tech support can help tell you what you can save or toss. They can even recommend one of their resellers to come and consult you on your project.

2) Place a new sheet of fleece on top and redo seams with new Kerdi band

No. You did something wrong with the base.

3) Cover with Red Guard (not ever sure if you can/should do that in this case)

Kerdi is waterproof material that does not need waterproofing.

 

[Jadnashua]

WHat thinset did you use? It looks like it may not have been mixed well or your choice of thinset wasn't great. With a premium dryset mortar, mixed properly, it is quite smooth and fluid. Kerdi seams become waterproof when you first, have the proper overlap (at least 2"), and proper mortar where the material is properly attached. To become waterproof on the seams, after embedding the stuff, the fleece on both sheets will be in contact with each other. If the mortar is too thick (either too dry, too sandy - cheap, or you applied too much and didn't embed things well), it isn't waterproof at the seam.

To check coverage, did you peel back any of the sheets to verify good coverage? You should have 100% coverage with no gaps.

 

[Jadnashua]

How long after installing the Kerdi did you wait to do the flood test? Schluter says a real 24-hours is required. Because of the way the cement cures in the thinset, if you let things dry out, and have a few more days, it might now be watertight...when cement cures, it grows little spikey crystals, and those can fill in some areas as it cures. That might be enough to seal things. But, if you had a text book install or even somewhat close, it would not have leaked after 24-hours. Typically, during a flood test, water might migrate maybe 1/4" into a seam, but because they specify at least a 2" overlap, normally, you'd have lots of margin for error. Having the excess mortar on top of the seams isn't an indication of a leak, but if it extends to too much between the sheets of a seam, it can leak through. Too much thinset, or too thick in consistency, or letting it dry out before trying to embed the sheets would have an excess of thinset, and that can allow water to seep through. It really does need to be applied with the specified trowel, and with a quality thinset. The cheap stuff just has too much sand and not enough cement in it.

FWIW, thinset does not 'stick' to Kerdi...the stuff gets held in place when the thinset is fluid enough to flow around the fleece fibers, and then, when it cures, locking it in place...not because it is stuck like with say a glue. Thinset does stick to other surfaces, which is what holds it to the backer board and then the tile to the Kerdi membrane (this is true for all of the sheet waterproofing materials, not just Kerdi). It is the action of the cement growing those crystalline spikes into microscopic imperfections that provides the bond to tile and the substrate, ending up in a very complex mechanical bond, more like Velcro than glue. What thinset did you use?