Due to a series of unfortunate events and being in a location where people are not known for being reliable, I've wound up with a 3/4" plywood floor in my master bathroom that is not level nor flat. I found out how bad when I lined up the square shower pan designed to go in the corner. Starting from the corner going clockwise, the corners are labeled 2, 3, 4, 1, with 1 being the high point. To get the pan level I had to shim the corners: 2 = 1/4" Shim 3 = 5/16" Shim 4 = 7/16" Shim

Under the floor are shims that were supposed to level the floor but they weren't cut correctly. I thought they were only a 16th out but I didn't realize there was a 3/8" drop in the floor from one side to the other (about 7 feet). I can't use self leveling on the entire floor as that would make it even with the 3/4" hardwood floor on the outside and the bottom of the door. Also, my ceilings are now too short for a full piece of drywall to be hung. I will have to cut each piece of drywall at least 1/2" short to account for the ceiling drywall, up to 1.5-1.75" short. 

Is it possible to put self leveling compound under the shower pan only or will that crumble over a few years time, resulting in a cracked shower pan?

Would it be better to put a 1.5" shim along the outside edges (0 -> 7/16 and 5/16 -> 7/16) and then pour the self leveling compound in the low areas?

Should I sand or plane down the 1/4" difference in the floor from 1 ->  2? Or do I need to rip everything out and start over again because it's going to make fitting the drywall "challenging"?

  • If you're using a prefab shower pan aren't you using a mortar bed or similar?
    – Huesmann
    Mar 18 at 14:43

1 Answer 1


Since the shower pan should be built to perform on a lever floor, I would pour leveling compound on the shower floor.

I don't believe that there will be crumbling or cracking.cracking

  • And nobody in the trades runs drywall upright. It’s way easier to go sideways for a bunch of reasons you’ll find in a search here. Mar 17 at 3:35

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