I have a newly constructed bathroom that has 2x8 floor joists, 16" OC.
Covered with 3/4 tongue and groove plywood.
I'd like to install floor tiles and have been considering a few of options:
1. tile over 1/2 cement board only
2. put another layer of ply (1/2) over the 3/4 and then tile over 1/4 cement
3. put another layer of ply (1/2) over the 3/4 and then tile over 1/2 cement
I would think that option 2 is best because it creates 1 1/4 ply for
rigidity and also has the cement board for bonding and waterproof. I would
screw both layers into the joists but I'm not sure if I need to put thinset
under the cement board since I've heard some yes and some no.
What do you think?
Try posting this question at:
It is a great tiling site where DYIers and pros discuss tiling issues.
I believe the correct answer would be 2 or 3. definitely not 1. You
also want the thinset between the cement board and the plywood. This
fills any voids and eliminates flex (which could cause cracks) due to
Also they seem to recommend that you do not want to screw the plywood
to the joists but to the sub floor. Post your question at the site and
they will do a better job explaining why.
Also do not use premix thinset! Apparently it is actually modify
mastic. Use the thinset that comes in a bag.
I think options 2 and 3 are overkill, but I'm not a tile setter. I did tile
a bathroom with 1/4" wonderboard over 3/4" plywood (2x8 fj. 16"oc) with no
problems years ago. The wonderboard was set into thinset and then screwed
into place every 6".
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