Gotcha. I'd say do the shower floor just like it was a nobelseal shower floor. Run the membrane across the floor and up the wall studs/blocking to a height about 3" above the top height of the curb. Check into that 3" minimum, I think that's what Nobel recommends. It can be nailed or stapled to the studs at the top edge of the membrane. You can detail the corners as they are supposed to be. The thing to watch out with when using thicker membranes like Nobelseal is that several overlaps can cause the bottom edge of the backer board to get "kicked out" into the shower if the overlaps will be trapped between the backer board and the wall framing. Regardless, there are several ways to detail the corners, you can fold them, or cut and overlap, or use preformed corners. Or tuck the membrane into the corner. With tucked, just make sure that the tucked part doesn't flop down in the corner, you want the top of the tucked edge to stay 3" above the flood plain, or 3" above the top of the curb. Each corner method has its pluses and minuses, see which is best for you based upon your situation. That build-up when overlapping, though, that's why you'll see references to notching wall studs, etc, when using thicker membranes. Anyhow, after the floor membrane is installed, install your backer board on the wall. Hold it about 1/4" or so of the floor. Fill and seal that 1/4" gap with a Nobel sealant or its equivalent. Now if you were running nobel membrane on the walls, you'd run it on the walls and butt it to the floor membrane, sealing that butt joint with a bead of nobel sealant. However, since you're using Kerdi, you can do one of a few things: 1) Install the wall Kerdi just like it was nobelseal membrane, butting the Kerdi on the wall to the Nobel on the floor, and seal the wall-to-floor membrane joint with sealant. This might be the best way due to the uncertainties about overlapping Kerdi and Nobel that I'll talk about in a bit. 2) Run the wall membrane down the wall and lap it onto the floor membrane 3" or so, thinsetting the Kerdi membrane to the nobelseal on the floor. If you do this though, you might need to run a couple of beads of sealant between the Kerdi and the nobel where they overlap on the floor. 3) Any of the other typical "Kerdi" options, which would be running the wall membrane down onto the floor like in #2 above, or using Kerdi band to seal them, etc. Again, though, where Kerdi overlaps Nobel, you might need a couple of beads of nobel sealant. Regardless of which you chose, I'd call Nobel and Schluter and run the options past them. I think option #1 is pretty straightforward and safe. My concern is that while a Kerdi-Kerdi overlap can be made watertight with a 2" overlap and thinset, Nobel requires nobel-nobel overlaps to have two beads of sealant to make that overlap watertight. Essentially, the Kerdi-Nobel overlap is untried and untested, so two beads of sealant might be best. But it's still untested. However, (and it's a big however) the overlap really doesn't really have to be watertight. With the nobel floor membrane running several inches up the walls, it's like a traditional CPE shower pan. There's your waterproofing. All you really need were you to overlap Kerdi on to Nobel is that the overlap not delaminate. With thinset being able to adhere to the fabric of both membrane, that shouldn't be a problem.

So, I'm getting ready to tile the shower ceiling. I have it all laid out. So, all I needed to do was get the non-sag thinset. Well, I can't find any (from the above) at either HD or Lowes. I read another post that someone else was having the same problem. I also checked a local tile store here and the lady didn't know what I was talking about. Is there anything else you can recommend? Would regular modified thinset work or would tiles start falling on my head? DH is asking about mastic adhesive. That doesn't sound quite right, so I need some advice, fast! TIA -Chris

I have a question regarding the cast iron shower pans that I just learned about here on this forum. We are going to have to have our shower floor torn out because we believe it was not sloped properly and have had ongoing mildew problems between the wall and floor. My question is this- would the cast iron shower pan be a desirable alternative to a tiled floor and what all would have to be done to install this besides tearing up the current floor and curb the glass sits on. Currently our tiled shower is a neoangle shaped shower that we would like to change to a regular square shaped one. Again, what would this entail and which would be the better route. Thank you so much.

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