With a square box installed flush with studs, 5/8 cement board and ceramic tile if I want the mud ring perfectly flush, should I use a 3/4 inch one?

  • 1
    Wouldn't that depend a lot (OK, entirely) on the thickness of the tile you're using and the required mastic notch size?
    – FreeMan
    Jun 2 at 13:05
  • @FreeMan yes. I contemplated posing the question in the form of a matrix :) Or just assuming it's more of a black art. But I thought I'd try just asking and see if there's any good advice.
    – jay613
    Jun 2 at 13:09
  • TBH, I don't see how there's any way of anyone answering this without knowing the thickness of the tile. However, I'm most certainly not the world's foremost expert on mud rings nor tile, so I'll just grab the popcorn (actually eggs & bacon - it's breakfast time!) and see what comes up.
    – FreeMan
    Jun 2 at 13:11
  • 1
    Well, the answer may be "you have to mock it up and measure it with your tile and your trowel and your backer board". We'll see. TBH right back, I'm happy to be at a point where I'm thinking about these things rather than just installing whatever jbox I have left over in the garage and realizing later what a mess I've made.
    – jay613
    Jun 2 at 13:14
  • 2
    You DO NOT want the ring perfectly flush a slight recess is much better because you don’t want the occasional tile variation to allow the cover plate to leave a gap.
    – Ed Beal
    Jun 2 at 17:08

1 Answer 1


I can answer "no" to the part of my question that suggests a 3/4 inch raise.

Here is a 5/8" backer and 5/16" tile (fairly common) with a 1 inch ring. Either this or a 1-1/4 inch ring would be the right size depending on the thinset thickness (here there is none) and the tile thickness.

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