Preferred Kerdi Shower Wall Material

[bcs001]

I cut away the Kerdi and paper layer of drywall where it was debonded and found the gypsum essentially intact behind the paper. So now I have about an 8” x 9” only as deep as the drywall paper depth.

I thought I could now use thinset and just patch the area but that doesn’t sound like the correct repair. I’m not familiar with eco prim grip but I’ll look into it. Is there any other primer type material that’s recommended? What about just an oil based primer like Zinzer Cover Stain? Buying a gallon of product to use a few brush fulls is not a great option but maybe no other choice here.
Bruce.

[jadnashua]

Cement and gypsum don't get along well together, so that's why you need something in between.

You might get by by using Kerdifix to attach the Kerdi back over as a patch...check with Schluter. You can probably use the rest of the KerdiFix for other things in building your shower, so the rest wouldn't be a waste (it comes in a smaller tube and a larger one designed for a caulking gun).

[bcs001]

I can see a tube of Kerdi Fix working for the entire patch area. The drywall paper was cut away for an 8”x9” area, I was going to patch with a single larger piece of Kerdi with about a 2-1/2” overlap on 3 sides and about 4” on the one side that wraps around an inside vertical corner.

Would I just apply multiple small parallel beads of the material extending out past the patch area and smooth the Kerdi with a drywall knife just like with thinset?

[jadnashua]

I'd use a notched trowel to spread the stuff, then use the flat side to embed the Kerdi membrane into it. You might just give Schluter's tech support line a call to confirm their thoughts.

[bcs001]

I contacted the local Schluter rep and he recommended just a latex based primer over the exposed gypsum (mask the Kerdi) and then thinset under a Kerdi patch with a 2” overlap. He said Kerdifix wasn’t recommended to join Kerdi to Kerdi.

I’m not an expert and only passing on what he recommended.

[cx]

Bruce, the Kerdi to Kerdi bond with thinset mortar is based upon the fleece on the surfaces of the Kerdi being in intimate contact and surrounded by the mortar. And as useful as the Kerdi Fix is for many applications, apparently it doesn't create that bond as well as the thinset mortar can. I would certainly advise you to follow their advice for your patch.

My opinion; worth price charged.

[bcs001]

CX, yes……I plan to prime and patch with thinset as recommended. I’m using versabond at the suggestion of others here and am satisfied with adhesion I’m getting on the Kerdi to drywall and Kerdi to Kerdi overlapping seams. I’m planning to continue using it for the floor pan, bench, curb, corners and bands.

[cx]

I would as well. See my warranty information below.

My opinion; worth price charged.

[bcs001]

I’ve already voided the warranty by using versabond…… you’re off the hook on this project.

[bcs001]

I'm progressing slowly thru this Kerdi build after being away for vacation. I'll take care of the drywall/membrane repair this weekend and start setting the pan and curb. I do need some guidance on setting the curb as it will be sitting on top of a material transition as follows.

I removed the 2-1/4 x 3/4 plank oak flooring under the shower pan area and put down 3/4 plywood over 1x6 diagonal subfloor but the curb will position over this joint where this plywood meets up with the oak flooring and extend approximately 2" onto the oak.

Can I just thinset the curb down to the plywood and oak over the joint or will I need to put down some kind of crack isolation membrane first? Can I put down a strip of Kerdi membrane for this?

[cx]

We're talking about a foam Kerdi curb?

[bcs001]

Correct, for my application its two 3' foam sections that came with the kit.

[Kman]

Are you leaving the oak flooring outside the shower?

[bcs001]

Yes. I can remove the finish off of the wood surface directly under the curb to help with adhesion of what ever needs to be applied.

[Kman]

Ok, the correct answer is that you would need to remove the oak flooring wherever the curb will sit.

Would the curb stay bonded to the oak long-term? I don't know, it might....or might not.

Personally, if it were mine I'd take the extra few minutes and remove it. If you have a rotary saw to make the long cuts and a reciprocating saw to get the corners it probably wouldn't take ten minutes.