Replies

1. 
   Peter_Volk/san_diego | Mar 03, 2001 09:13am | #1

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   My understanding is, if the plywood is solid, then use your mortar to spread over the plywood to make a smooth surface. Then it will be easier to trowel on the mortar smoothly, so you can install the tiles as needed. Do not use thinset as this will crack if any of the subfloor moves, use flex-bond material that is flexible and won't crack. By the way, I'm not a tile contracter, just a handyman that's done a dozen or so tile jobs, so take my advice for what it's worth.

1. 
   Qtrmeg_ | Mar 03, 2001 04:03pm | #2

   *If you are worried about the height of the finished tile floor remove everything to the subfloor, then add plywood underlayment (or backer brd if you wish) and tile, (with thinset). The subfloor and underlayment should be at least 1 1/4", with the underlayment a minimum of 1/2". I could get into why I don't like to glue down underlayment, but you will soon see what I mean if you decide to remove these layers.As far as adding tile to the ply you have, good luck. I wonder how well it is "glued" to the oak, and how much adhesive residue would remain on the surface once you remove the vinyl. As you are going to sell this house, why don't you just install new vinyl and save a bunch of work, and let the new owners decide how to decorate their new house?

1. 
   Buck_Olmsted | Mar 12, 2001 11:04pm | #3

   *I disagree with Peter. I would definitely use thinset. It will give more protection to the 1/4" plywood should water want to get into the grout. If you have any movement in the subfloor then don't tile or tear the 1/4" ply off and replace with 1/2" or better yet 5/8" CDX ply. Peter is right in that if the subfloor moves thinset will crack but then using flex bond doesn't help because the movement will likely crack the tiles themselves. Tile should only be laid on a very sturdy surface that does not flex or ultimately you will have problems somewhere. I'm an architect and in specifying a tile floor I would never specify anything less than a 3/4" subfloor for a surface to be tiled. In my own house I used 1" tongue and grove CDX ply that is glued and screwed to the TJI's.

1. 
   marko_maryniak | Mar 12, 2001 11:48pm | #4

   *What does CDX mean? I am not up on my acronyms. When I put my slate in by the front door I was told to lay it over at least 1-1/4" thickness, i.e. 3/4 subfloor and 1/2 substrate. Anybody else heard of this or any other rule of thumb?

1. 
   Buck_Olmsted | Mar 13, 2001 12:08am | #5

   *CDX - This is the designation that is given to exterior grade ply. It is much more resistant to water than other plys.

2. 
   Heck_ | Mar 13, 2001 01:59am | #6

   *C= c grade one faceD= d grade other faceX= eXterior glueJ.W.

3. 
   Ron_Teti | Mar 13, 2001 04:13pm | #7

   *I would leave the vinyl on nail hardibacker through the 1/4 ply to the oak hardwood and use the thin set. The height difference by removing the vinyl will be very little. The vinyl will act as a water barrier to help protect the substrate from damage. You might have to do some cutting to adj. the door height and add a extension wax ring for the w/c. Just my opinion.

2. 
   Jeff_Leftwich | Mar 13, 2001 04:13pm | #8

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   We will be refacing our bathroom in preparation for selling. It's a small room, about 30 square feet. The floor is currently sheet vinyl glued to 1/4 inch plywood which in turn is glued to the original oak hardwood. We're planning to tile it over. I was going to pull the vinyl and lay down backer board over the plywood but that would increase the floor height by a significant amount. The plywood is solidly attached to the oak. Does anyone see a problem in tiling over the plywood directly as an underlayment? Thanks for the input.

3. 
   illusionsgame | May 08, 2019 06:15pm | #9

   What about painting a new plywood floor? Is this a thing? thanks

4. 
   tfarwell | May 17, 2019 10:47pm | #10

   Backer board is ideal, but you can lay tile on the plywood. Don't lay it on the vinyl - get that out of there. Use a polymer modified thinset so it will adhere correctly.

5. 
   illusionsgame | May 30, 2019 12:05pm | #11

   Just an update: I did it. Came out fine ... we will see about the wear and over the yearsI took painters advice on this site...https://www.bradthepainter.com/painting-plywood/ .... I guess the prep and the quality of the actual plastic that you lay down is really the thing.
   If you are thinking of painting a plywood floor... go for it