Quick question on leveling sub floor for Schluter Shower. Between plys or on top?

[patma]

I searched this forum b-4 posting but could not find a similar question.

My 48X48 3/4" subfloor is out of level 5/8" from right side (exterior wall). The level is consistent for the extire 48" run. I am planning on adding a second layer of 3/4" exterior plywood as additional sub floor support before installing the Schluter pan.

Question. 1) Should I level the floor between the two sheets of plywood using self leveler? or thin set?, - basically sandwiching the leveler b/tween the ply or, 2) Install the ply to the ply and level the top and then thin set the pan in place.

(If Thin set is better, I'd like to use that since I have enough already. However, no problem using a poured self leveler as I am planning radiant heat flooring too.

Thanks in advance for any help

[jadnashua]

Do not put the leveling material between sheets. When you screw the second layer through, it's likely you'd crack it and that may cause voids and crunching sounds.

If you're going to pour a self-leveler over the floor, I'd consider doing that in the area where the pan is. Thinset will stick to it fine. If you don't want to do the heating layout before the shower pan is installed, you can make a dam with a 2x4 or some closed cell foam, backed up with something to keep it in place, and pour it. Thinset doesn't like to be applied that thick. A medium bed mortar could, but then you'd end up with another bag of stuff you didn't need to dispose of the remainder. Thinset isn't a great leveler, but I have used it when things only need a small amount, and it does work. Prefer not to use it on a floor, as it isn't as strong when thicker. Not really as big a deal since the load is spread out over a large surface, but still, it's not designed for that, so why chance it?

If you had a taper jig, you could make some tapered shims cut from a 2x material full length, spaced maybe every 6" or so to create a level surface, then screw and nail them and the new sheet in place. It's hard to make them nice and consistent, but it's doable with the right tools.

[patma]

Wow... Taper jig is exactly what I'll do. (never even thought of that) I made one a few years ago for some small Amish tables I "attempted" to make.. The jig was the easy part.. the legs tapered all over the place...
I re-checked the floor and found it to be exactly 1/2 out.. so a few tapers, screwed and glued is the answer- for me.

I over think this again... Have to keep it simple if possible.

Thanks for the time and info.. learned a lot again today.

PS: "The Americans spent $1,203,400 dollars developing a pen that writes in outer space... the Russian's use a pencil"