A family member helped me install some cement board in my shower, but the cement board and drywall aren’t level. It already has two coats of red guard and is basically ready to tile. Can I use thin set to level this out, let it dry, and then tile as normal on top of it?

Pictures attached. I am reallyyyy trying to prevent having to rip it all out.

Any solutions would be unbelievably appreciated. Gotta get this done by next Tuesday.

Thank you in advance!!enter image description hereenter image description here]![enter image description hereenter image description here

  • I use Denshield to avoid this very problem, it is 1/2" thick like the drywall, so no disparity in transition.
    – Alaska Man
    Feb 21, 2020 at 20:54

2 Answers 2


In some cases I have wanted the tile base lower than the sheetrock. This way there is not a large ledge for water to collect on. You can float some thin set to the surface but make sure it is completely dry prior to tiling and make a large taper or it will be noticeable.


Yes you can float on top of red guard before tiling.

If you want a perfectly flat wall and assuming you are tiling then the proper way to do this is to put some 1/2" thick strips vertically make sure the strips are plumb and put a level across the two strips and make sure they are level with each other. Then you can put a fair amount of thinset and screed between the two strips once the thinset sets up a little you can remove the two strips and fill in.

Depending on your tolerance for perfection and how much extra time you want to spend getting your tile flat, you could also just use modified thinset and your level as a screed to make the areas you've indicated flat across the width of the wall.

I'd probably still do the red guard again on top of the float as thinset is porous and will absorb water but the water would eventually come out and you have a waterproof barrier so you don't have to do that.

I'd go with a polymer modified thinset for better bonding when flattening it out out.

I would use epoxy grout as well for a better waterproof system and to avoid grout that stains or needs to be sealed all the time.

This is the screed set I use. https://www.amazon.com/Bon-24-125-1-Feet-6-Inch-Aluminum/dp/B0006MWKY6/ref=pd_sbs_469_1/144-2317399-1643469?_encoding=UTF8&pd_rd_i=B0006MWKY6&pd_rd_r=51a35c9b-c720-4664-848a-0d0c625bb6e9&pd_rd_w=QS6te&pd_rd_wg=ieW41&pf_rd_p=74b54c94-7195-4620-ba51-7d167ac58a58&pf_rd_r=EN32SKAZ9XJT4RQA0EP8&psc=1&refRID=EN32SKAZ9XJT4RQA0EP8

  • Thanks so much. So what should I use? Something like thinset, and basically use that as like a self leveling compound on the wall to even everything out? Then let that dry, and tile on top? Feb 21, 2020 at 13:38
  • Hi. Would you please elaborate on your answer? It really presumes a fair amount of knowledge. (No, I didn't downvote it; that was someone else...) Feb 21, 2020 at 14:47

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