jjaazzy, this is one you want to take over to John Bridge's site. I've never used Nobleseal, so I'm not sure about their installation instructions. There's a guy over there that goes by the name E3 (Eric). He's a big wig at Noble, and he'd be able to help you better than anyone.

Thanks Bill will do!

I'm curious...

Why the Nobelseal/Kerdi hybrid shower? Why not just Kerdi?

And are you putting the nobelseal membrane over a Kerdi foam tray or over a Nobel proslope foam base?

I'm wicked confused. Which is not unusual for me these days!

Thanks for responding Mongo, well the trench drain has a Noble seal flange already in place around the edge, about 8" around. Being that I am in uncharted waters I told the company send me what I need! So with that I got the Styrofoam the Nobleseal material and the caulk. We will kerdi the walls. I have to say that the Nobleseal material is nice, it's a bit thicker. Maybe when working with it that's not a good thing but it is nice. Now I am over in the John Bridge forum looking for info but I will just have to post it cause nothing is exact to my situation. (Really? you don't say!): )

When you post, ask specifically for E3 to respond. If he doesn't see it, someone will email him.

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.

Thanks Bill & Mongo! Bill I had already sent my note over without the shoutout directly to e3 so we will see what happens with that. Mongo gave me a very detailed outline and I think I will be ok. He said go up 3" over curb and there is not going to be one so I think I will go up 5". Quick drain suggested 4". I also like the idea of using the mixture of thinset I did for the floor/Styrofoam and a heavy bead of caulk at the base for the walls, that will stop any wicking. I have the durock up already so I will use the cut and overlap technique shown on Nobleseal for the floor coverage. I will see what happens with post over at JB and see if he picks it up. Thank you Mongo you eased my fears and confusion and I think I will be ok. (please please please)