I am renovating my kitchen and bathroom. My house was built in 1952. I will be installing ceramic floors in both. I have 5-1/2 x 3/4 tongue and groove boards running diagonally and nailed to the floor joists.

If I use 3/4" t&g plywood followed by 7/16" cement board and then tile my floor will be too high. What is the best method to prep for tile?


3/4" t&g plywood (not OSB) over 3/4" boards would be adequate by itself, in my opinion. The industry often suggests 1-1/4" as a minimum, and you'd exceed that.

  • I would agree in many older homes that had solid floors like yours tile can be put directly on the plywood, I did a job for my mom over 30 years ago and it is on plywood over T&G and it still looks good although a bit dated.
    – Ed Beal
    Feb 9 '18 at 23:23

Only good answer is go down. Cut the substrate boards, install quality 3/4" tongue & groove plywood, install cementboard.

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