I need to level the base of a shower and the plan is to pour self leveling underlayment.

The initial plan to shim the shower explains why I removed some tiles. I've moved on to plan B, which is the self leveling underlayment.

Essentially, should I tile before pouring the underlayment in hollow where the base is, or it doesn't matter? My guess is I should probably tile first as it would help to contain the underlayment (slopes away from wall opposite faucet, edge of cabinet shows it being off by 1/4"). However, this isn't my field of expertise.

Side note, plan A was to simply shim it, but then the base edge wasn't level and sloped inwards. I figured this wasn't optimal for when I would have to put the doors back on.

Shower Pic

  • I see other issues first. A joint in the subfloor right at the edge of the tile, a lot of small pieces of plywood underlayment, and not enough room to flow the self-leveling underlayment. How far is the floor out in that little space? Other than the few things I mentioned which are important, I see nothing wrong with the area. The shower has been there for a while according to the old caulk/grout line at the bottom of the curb?
    – Jack
    Mar 29, 2015 at 15:39
  • Is the radius cut of the plywood to the curb? or does it go under the curb to support it in some places. It looks in some places, like the curb may even be setting over a hollow left by the plywood not passing under it. Is this where you plan on pouring the self leveling underlayment, in that hollow? Sorry about all the detailed questions, it matters how it is done for the longevity of the floor.
    – Jack
    Mar 29, 2015 at 15:46
  • @jack Indeed, the underlayment would be poured in the hollow where the shower is (which would be removed prior). The shower has been there since the properly has been built, four years ago. The plywood is cut along the base of the shower creating a hollow. I hadn't taken in account for the edge of the tile being on the seam like that. Thanks for the reply.
    – TechFanDan
    Mar 29, 2015 at 16:19

2 Answers 2


personally i don't tile atop plywood. i'd pull the 3/8 then concrete backerboard would go down first over the subfloor. then i'd shim the shower. if the shower is heavy i might then give it a week to let it compress the wooden shims and re-test for level and re-shim if needed. then i'd tile. some people are less retentive than me though and that's okay too : )

  • I tried the shims, but the edge of the shower where the doors go, featured an internal slope. I figured it may impact door installation afterwards (affecting seal, etc). I also had to remove the drywall around it to get at the screws securing it to the walls as I couldn't shim the side nearest the wall. At this point, I figure, might as well remove it and attack this issue at the base.
    – TechFanDan
    Mar 31, 2015 at 12:29
  • fair enough... then i'd self level. i think i'd get a solid backerboard base down first.
    – codemonkey
    Mar 31, 2015 at 12:34
  • that's the alternative that I was considering... not sure how to level this sort of thing, sand it? This would be cheaper than the self levelling stuff too.
    – TechFanDan
    Mar 31, 2015 at 12:37
  • just learned what backerboard is, assumed something else. In any case, I was considering adding the same stuff that was found under the tiles, underneath the shower base, how would one level that?
    – TechFanDan
    Mar 31, 2015 at 12:41
  • 1
    the backerboard isn't about levelling. you'd still need to self level on top of it in this scenario i suppose. the backerboard is just a superior substrate to tile on. especially for floors where the weight of people walking flexes the subfloor. backerboard fights the flex. gives you a more solid floor... fights cracking in the grout, etc.
    – codemonkey
    Mar 31, 2015 at 12:41

You would definitely not tile first. Also I wouldn't use a self leveling compound here either. You would shim (roofing shingles for something like this) or cut out some plywood to fit. You can then use thinset to fill in any cracks to to point your shower towards the drain.

If you decide to still use a self leveler I would block off the area 2xs and putty - and pour from there, install shower and then chisel out and extra self leveler interfering with tile install.

The other option is to chisel, scrape, plane down the area that is too high near the wall. Really hard to tell you the best way without seeing what is under and under under.

  • the shower and tiling area aren't at the same level. The tiles are sitting on 3/8, thus the shower is on plywood in a 3/8 hollowed out area. The floor has sagged which explains the dip IMO. I will now attempt to block off the tile area instead, per your suggestion.
    – TechFanDan
    Mar 31, 2015 at 0:33

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