Hello,

I need to level the floor under the 54" square Onyx shower base I'm installing. The bathroom is large (13'x15") so I don't really want to level the entire floor. It's ~5/8" out of level, with the high point at the back wall, low point near where the door will be.


The problem is that the leveler (LevelQuick RS) requires metal lath & min of 1/2" thickness over wood. If it's 1/2" at the highest, it'll be 1 1/8" under the door. I plan on adding 1/2" plywood before putting the vinyl tile down, but that will leave ~1/2" of the leveler exposed. I can put 1/4 round around the shower pan, but that gets tricky at the rounded corner and will probably look tacky.

Can I get away with making the leveler thinner, since I'm going under a solid, 150lb, cast acrylic (or something like it) base? The bottom of the base has some small voids in it, but is mostly ground flat. Ideally I put the leveler in and feather it to nothing at the wall so that it's ~5/8" thick at the max by the door.

I don't want to cut corners and find I have an unstable base later and have to tear things out and redo them, but I'd like to avoid a bunch of exposed leveler that I need to hide later.

 

Lay your onyx base down, and draw a line around it. Then remove it and put a 1x4 on that line, screwed to the floor temporarily. Pour your self leveller inside that form to level just that area.

Then remove the 1x4 form and put your 1/2" plywood subfloor down around the onyx base... once your flooring is on, caulk it at the doorway.

Use a self leveller that can go to a feather edge. It's all going to be under the onyx anyway so it's not like it's going to see traffic and crumble. It's just a shim.

 

As you can see in the picture, I've already done most of that and I'm ready to pour. The leveler I have says it'll go to a feather edge, but it also says it needs a metal lath and a minimum of 1/2" thickness over wood.

As you said, though, I just need a shim. So I'm thinking (hoping) I can ignore those min requirements and pour thinner. Looking for the thoughts of those like you who do this often. This is my first time.