enter image description hereI recently tore up my half bath tile and quarter inch underlayment to eventually extend my LVP to the bathroom. I’m wondering what I should buy to meet the toilet flange. The tile I had in there was a pretty thick boy with the mortar. The flange is about 1 inch above the subfloor.

I was thinking 3 quarter inch concrete backer board or half inch backer board.

I also need to meet the transition to the next room, but it looks they are a bit different.

Any opinions are greatly appreciated! Thank you!

  • 1
    You may be able lower the flange rather than raise the subfloor if that would suit your needs better. I am a bit confused as to what heights you need to meet.
    – RMDman
    Commented Apr 3 at 0:19
  • Please post a photo Commented Apr 3 at 2:46
  • Toilets accommodate some protrusion of the flange. Check yours so you can minimize expense (and maybe a transition at the room entrance). I suggest you revise to provide more contextual information so we can be most helpful.
    – isherwood
    Commented Apr 3 at 13:24
  • Then, 3/4" cement board isn't readily available, and cement isn't needed (or even appropriate) under vinyl.
    – isherwood
    Commented Apr 3 at 13:26

1 Answer 1


Optimally, your flange should end up sitting proud of the finished floor about 1/4". Whether 1/2" or 3/4" underlayment works best for that will depend on your vinyl.

If there is no clean way to get 1/4", lower is better than higher because various spacers and wax ring options will still allow successful toilet set.

Depending on the type of existing flange, pipe, and floor, lowering of the existing flange could be easy or really tough (to DIY); however, a skilled plumber would make short work of it regardless.

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