Subfloor replacement, 1/2 to 3/4

Discussion in 'Ceramic and Stone Q&A' started by Matt688, Jan 5, 2021.

  1. Matt688

    Matt688 New Member

    Im in the middle of a bathroom remodel and noticed some water damage on my subfloor. My house is pretty old, from the 60's and I know the bathroom has not been remodeled since then. I decided to rip it all out and replace the subfloor for the room.

    The subfloor I ripped out is 1/2 and had a full inch of poured concrete between the subfloor and the tile.

    I decided to go with a 3/4 plywood to give the tile more support - I plan on using the schluter ditra over concrete backerboard, it looked easier.

    My question is will I have a difficult time fitting the 3/4 subfloor when the rest of the house is 1/2 inch?
    I know I will have some more space since the concrete was so thick

    Thanks - this is my first major floor job.
  2. What’s the joist spacing?

    concrete backer board and Schluter is somewhat redundant.

    I’m not good with wood subfloor specs though.

    Did the toilet drain leak causing the rot over time?
  3. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    So you removed the subfloor right down to joists? Pulling from the top of my head tile spec is 1.125 inches over 16 O.C. joists. I do believe that 3/4 subfloor and Ditra would get you there. To be fair, there is no minimum for tile beyond 5/8 t&g plywood but then it all comes down to L/360 deflection calculations. That nonsense can get confusing and hard to determine so personally I like a solid inch of wood. Over 5/8 i would add a 1/2 inch piece. 3/4 t&g would likely get you there as far as deflection calculations but with tile i am happy with safe over sorry.

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