Tile over plywood?

Can tile be installed over plywood (external grade)? Or does it have to be set on backerboard?

 

Maybe, depends what's underneath the plywood.

 

Concrete foundation to the house would be underneath the plywood.

 

No, he means like what size joists, spacing and unsupported span and how thick is the plywood there now?

 

There is no plywood there now. That is what I am trying to figure out. What do I need to put down over the concrete foundation before I put in tile? I want the floor about 1 1/2" above the foundation so I need some sort of subfloor.

There are no joists.

 

Oh, so you have a concrete slab and you want to raise the final floor height 1.5" over what it is now, is that correct?

How about a mud floor base and set the tile on it with thinset. There is no way to screw plywood down onto a concrete slab, at least not in any way that would support tile. You would need some wood slats put in first as sleepers but they would have to be thick enough to hold the screw that is used to hold down the plywood so I think your overall floor height would exceed the 1.5" you are shooting for.

If Tileman sees this post he will have some good ideas maybe. He is very good on cement floor issues like this. (Did I just put the pressure on you or what? )

 

I could set the plywood with concrete nails. At least I think I could.

 

No pressure, MK, Tileguybob said it exactly, sleeper system or Mud job, mud is the way to go, you could also use self leveling compounds, but that would be VERY expensive.

NO, you can noy install plywood or any backerboard over concrete directly for tiling.