Ceramic Tile subfloor prep

Discussion in 'Ceramic and Stone Q&A' started by Polara, Jan 13, 2021.

  1. Polara

    Polara Member

    In the middle of updating the bathroom on a 60's house and wanting to use ceramic tile. Original construction was 2x10 @ 16"oc; 6" T&G (3/4 thick) installed on a 45 deg angle, with 5/8" plywood over that - and carpeted...... Rearranging fixtures so had to remove the plywood and replace some of the T&G now need to know what to use on top of this to use ceramic tile. Also considering installing some floor heat in the walk track (Northern MN).

    Thanks for any and all assistance.
     
  2. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    If I understand your floor assembly correctly then I would say deflection in the floor will not be an issue for you.

    As for heat, you could use ditra heat, it is very simple and a cable matting system. Mapei has one as well but I cannot recall the name right now. That would take care of a decoupling membrane and be used for heat.
     
  3. Polara

    Polara Member

    Is 1/2" CDX adequate for the underlayment? (I hope that's the correct term.) The 5/8 had to be replaced and all they had at the local yard was 1/2. And the ceramic can be laid directly on the plywood? of course using appropriate thinset or other stuff - plan on hiring that part just want to do the basic preps. And the heating system is thin enough it can lay on top of the plywood?

    Sorry for all the questions, just a hard headed retired electronic tech here.
     
    Last edited: Jan 13, 2021
  4. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    If your 3/4 t&g and 5/8 is in good shape there is no need for 1/2 inch cdx (definitly right) but more is never worse lol.
    The only system I am aware of for embedding in mortar bed for heat is cable mats. Look at nuheat for an idea. Personally I would get heat cable and route it into my plywood but that is probably against some building code or other.... you might want to look at mats.
    In all honesty though, if you have the height Ditra Heat membrane and cable is a bloody good system.
     
  5. Polara

    Polara Member

    We were typing at the same time.......lol The 5/8 had to come out.
     
    • Like Like x 1
  6. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    I wasn't really paying attention when I read your last post but yes, half inch over 3/4 shiplap will be fine for tile.
    It really all comes down to L/360 span ratings but in a bathroom im gonna venture a guess that 1 1/4 of wood is gonna work great. If not the bathroom I did today is gonna be in trouble
     
  7. Polara

    Polara Member

    Great, thanks tons. Now I got tons of screws to drive........
     
  8. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    yes, yes you do :)
     
  9. Polara

    Polara Member

    One more silly question please - I have a floor dimension of 8'3". Am I better having the ply cut to 7' and 1'3" or 8' and just a 3" strip adjacent to the wall?
     
  10. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    I hate wee strips and if you have excess ply go for it but if you needed to buy more plywood to make it happen I would say don't bother.
     
    Last edited: Jan 14, 2021
  11. Polara

    Polara Member

    Thanks, kinda my thoughts also.
     

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