Kerdi over drymix mortar

[Rooferyan]

Hello everyone,
I seem to be making this shower pan as difficult as possible and need some advice. I installed a 5 to 1 mix of portland cement and play sand as a preslope with a 1/4" to a foot fall and it turned out well. I then installed the pan liner and set my linear drain. I applied another layer of drymix 3/4" from the top of the drain. Now I have decided to use Kerdi on the shower floor and walls for their warranty and this system makes sense to me. My question is can I apply another layer of deck mud directly to the deck mud that is there and has been drying for several hours or do I need to give it 24 hours then thinset slurry then deckmud to the top of my drain, allow to dry and install the membrane?

[Carbidetooth]

Welcome Rye. This doesn't really address your question, but I wouldn't consider either option viable, assuming I had to stand behind my work.

Also of concern would be how you intend to tie Kerdi membrane to drain itself, which was presumably designed for a conventional shower receptor installation.

Is redoing the slope entirely out of the question?

I should add that any variation from Schluter recommendations is going to void any warranty you might otherwise have.

[Rooferyan]

No biggie, Tearing it out is definitely an option. Down to the pre slope or to the deck? I recessed the area blocking in between the floor joist to bring it down flush with the top of the joist. I will load some photos.
Thanks a ton for your input.

[John Bridge]

Hi Rye,

You'll have to change drains if you switch to the Kerdi shower. That's going to mess up everything you've done. If you do want to do that, I suggest you remove what you've done and start over.

[Rooferyan]

I feel like that is a lot of time and money if it’s not needed. If it is needed then it’s priceless to catch it now. I will load some photos and let me know what you think.
The hardi backer is in place to set the drain off if. Fir attaching the linear drain I found a detail on line. I will grab a screen shot of it and post it soon

[Rooferyan]

So this is where I’m at now I remove the top mortar bed and I’m down to my pan over the pre slope. I would like to keep my pre slope and liner and add the mortar bed at the correct height with the correct Kerdi line drain. Or if that won’t park I would go with the water in water out method and use the drain I have. I also have this Kerdi drain adapter kit but I don’t believe it will help with the Kerdi line drain.
The Tigerpaw on the wall is felt on steroids, synthetic underpayment that has taken the place of felt paper. I figured it was better than plastic or felt.

[Rooferyan]

Photos for the last post

[Kman]

If you're keeping the liner, you won't be able to use Kerdi, at least not on the floor. Using Kerdi or the Kerdi drain on the floor would necessitate removal down to the subfloor.

[Rooferyan]

After a lot of thought and some more research I don’t think I gain much by using the Kerdi on the floor other than the warranty. As long as I ever need it. I feel like the traditional water in water out is just as good when done properly as a membrane system on the shower floor. I have removed 2 now trying to get it perfect, if this 3rd time isn’t a charm I’ll get a custom pre-sloped pan. As far as warranty I work with different manufactures every day for my entire adult life in roofing, waterproofing, siding and almost never does the product actually fail. Every now and again but almost always It’s an accidental installation error or poor workmanship. If the product fails they will replace the product regardless. Not a very likely scenario though. I have not found anything that says that the traditional way is no good and don’t use it. I mostly find that Kerdi is easier to work with the reason most seems to go with it and it is a great product.
Any info that doesn’t come up on a quick google search out there that anyone could point me towards is greatly appreciated.

[Tiger Mountain Tile Inc]

Hard to tell from the photos but it looks like the liner doesn't go over the curb. Rather, the curb looks like bare wood. Is this the case?

Can you post some more photos of what your liner looks like since it's the critical part of the waterproofing? Did you do a flood test on it after you put the liner in?

[Davy]

Hi Rye, lets go back to your pictures in post 5. Is that the black pan liner I see sticking out of the mud bed a few inches near the drain? If it is, the liner should go up several inches above the curb height and also cover the curb. Also, it's best to glue on pan corners where the curb meets the walls. You might check out the shower construction thread in the "liberry".

Edit; Looks like James and I were typing at the same time. What he said.

[Rooferyan]

The curb is made of brick pavers and mortar, and it is over the curb.
The last picture in post 5 is my pre slope. I used ice and water shield instead of felt. The liner turns up the wall about 18”

[cx]

Originally Posted by Rye

The curb is made of brick pavers and mortar, and it is over the curb. (emphasis mine)

What is over the curb, Rye?

Originally Posted by Rye

I used ice and water shield instead of felt. The liner turns up the wall about 18”

I think there's some confusion here. While Ice and Water Shield is fine for the edges and valleys of your roof, it's not something you would use as the waterproof liner in a traditonal shower receptor. You need a PVC or CPE material, or some other approved material not known to me, but I don't believe having that Ice and Water Shield in direct contract with Portland cement mortar is a good idea.

And that is not where you would use roofing felt either. The roofing felt could be used as the wall moisture barrier, but not in the receptor.

I'm thinking what you need to do here is remove everything and start over with your new waterproofing system, Rye.

My opinion; worth price charged.

[Rooferyan]

So I removed the top mud bed and cleaned everything up really good. I removed the bolt on compression seal part of the drain and cleaned out all of the grooves and holes to ensure there are no issues with the weep holes and reassembled that. I tested the weep holes and they where performing well. I did about an hour water test with no issues. I’m a Florida state certified licensed roofing contractor and after some research on showers I found a spec calling for EPDM as the shower pan in a large custom shower and found some people do use it for this application and I have done and still do a ton of EPDM so I went with it. I shot the wall below with a flir infrared and tested for moisture and it looked good, no elevated moisture. The water proofing part I have down very well but not the compatibility with the other shower parts. Like making sure I’m not trapping moisture or creating condensation. I have a co worker that has done shower remodels as a job years ago and will come show me how and make sure it is being tiled correctly. Just want to make sure the system is a good set up and will perform properly. I have the Ditra heat to install on the rest of the bathroom floor and should have my vapor barrier and hardi backer finished this week and can move that direction next.
There are so many different specs out there for all of these items. I am assuming that there all the same as the exterior products that I work with, as long as it’s installed correctly as per manufacturer specifications they will work. How long they last and the amount of maintenance needed is the compromise for cost.

[cx]

Rye, it appears in your photo that you have mechanical fasteners in your wallboard that are at a level much lower than a couple inches above the top of your curb. I'm seeing that correctly?

I'm not questioning your roofing expertise, nor your knowledge of roofing materials, but in your location your shower will see a hundred times more water than will your roof. And I doubt that your roofing materials are ever in direct and constant contact with Portland cement. Please keep that in mind.

Being "tiled correctly" is the lowest level of technical consideration in a shower construction. It's the long term waterproofing that's the primary concern.

My opinion; worth price charged.