What are your drywall/cement board/framing flatness tolerances for tile supporting walls? I am rebuilding half of a frame and it is a challenge to bring all the studs in the same plane. I do know about the tricks used to straighten studs but I am thinking there must be some tolerances in this respect

Update: this is related to this thread. Can I use corner brackets to rebuild a wall frame that has the horizontal 2x4s extended in an adjacent room? I build my second half of the frame and now I am trying to align it with the existing and it seems to be complex since the top and the bottom plate could be aligned using a long level as straight edge but then studs might not be in the same plan with the other half that is already there. I am using a vertical laser and double checking with the 8' straight edge-level

Update2: this guy is doing it using thinset. Is this normal? (you can call this floating the cement board I guess) https://youtu.be/Fls1asNV9ug?t=1141

Update3: this guy is floating the tiles instead

  • 1
    I don't use drywall for tile. Given the expense and labor of installing tile, the slight upcharge for using proper backerboard is a minuscule investment in having a proper foundation for the job.
    – Ecnerwal
    Commented Nov 25, 2020 at 21:15
  • Agree with Ecnerwal in the use of an appropriate backer board. If you're worried about straightening studs, use the steel ones.
    – JACK
    Commented Nov 25, 2020 at 21:34
  • Cementboard is ok? I want to make sure the studs are in the same plane but it is not perfect
    – MiniMe
    Commented Nov 25, 2020 at 22:41
  • Yes. Unless your walls are severely curved, the rigidity of the cement board, the "depth" of the adhesive, size of the tiles, etc. should eat up any slight unevenness from the studs. It will come out perceptibly flat. Otherwise you need to replace or shim the studs I'd guess. Post some picture of the existing studs and maybe include some way of seeing the variation in the picture (straight edge or something) so we can see what you're dealing with.
    – gnicko
    Commented Nov 25, 2020 at 22:44
  • see the update. Re: re the adhesives eating up the uneveness -this is why I asked, I suspected that the adhesive could be used to compensate that but I was not sure how much ... some docs on the net are saying 1/4" for 10' but not more than 1/16'' for 12" but those are theoretical standards probably
    – MiniMe
    Commented Nov 25, 2020 at 23:31

1 Answer 1


Just use drywall cardboard shims or sistered studs to bring the studs into plane. TCNA says 1/4" deviation over 10'. If using large format tile, trying to level with thinset after will take way longer and be more frustrating than the time it would take to make sure the walls are straight and plumb

Edit: Since you like Sal youtube videos this is the one you want https://www.youtube.com/watch?v=PCUWkbG060s

  • yes your answer seems to be right but I was wondering if the cement board will in fact hide small imperfections
    – MiniMe
    Commented Nov 25, 2020 at 23:37
  • define small, it will follow the contours of the studs if you are wondering so if the studs are out of plane the cement board will be wavy or curved once they are screwed in.
    – redlude97
    Commented Nov 25, 2020 at 23:53
  • will follow if you screw the cement very tight but I am guessing the board has some rigidity by itself and it can stay flat if not forced to follow the studs
    – MiniMe
    Commented Nov 25, 2020 at 23:56
  • you won't be able to embed the screw heads if you try to leave a gap behind the boards
    – redlude97
    Commented Nov 26, 2020 at 0:01
  • you can predrill that like you would do with wood
    – MiniMe
    Commented Nov 26, 2020 at 0:02

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