Installing 1/2' thick ceramic tile over oak floor

[Mikepier]

A few weeks ago I asked if I could tile over oak floor area in my foyer 4'X15' and everyone suggested using some kind of underlayment. Recently my wife and I picked out a tile that is 1/2" thick and is 11

3/4" X 11 3/4". This tile looks a lot more beefy than ordinary tiles and of course costs twice as much. Now the problem is because it's 1/2" thick it would be a problem heightwise even if I used a 1/4" backerboard. So my question is will this tile be less likely to have problems if I go over the wood floor because it's so thick even if I screwed down the floor at every joist. By the way my combined subfloor and hardwood thickness is 1 1/2".

[Noozer]

What condition is the original floor in? If it's in decent shape I would be very hesitant to cover it at all, or at least to permanently marr it up.

[Mikepier]

The floor is kind of marred up already. I removed the old tile and

1/4" plywood that was on it originally. Structurally its fine. We have oak floors throughout the first floor, but we liked it better to have tile in this entryway because it was easier to clean plus the tile floor continued into the kitchen, which I am remodeling.

[Big_Jake]

The tile will likely be ok, but the grout will crack.

I recently did tiled two kitchen floors in a duplex. On the advice of a tile pro, I put down ECB membrane, which is an antifracture membrane, and I tiled over that. I had exactly enough membrane to do both kitchens, and skipped a small area that would be covered by cabinets. I tiled and grouted, and all the grout lines cracked in the small areas where I hadn't used the membrane, in less than 24 hours.

JK

[Manster]

An 1-1/2 is a pretty thick sub-floor already without adding a 1/4" board. If the oak floor is roughed up a bit and the joists are not spaced too far apart and there's no flexing between them, you should be fine. Someone mentioned sealing the sub-floor first, but I disagree. A sealer may interfere with the adhesive you use for the tile.

[samurai]

I would be hesitant to put over oak floor, as it may let loose or float(due to heat and humidity), and result in cracked grout. Oak floors are just nailed in, and will 'creak' over time. Ever had a squeeky wood floor?? Especially in a high traffic area, you want it strong as possible.

To do it properly, remove the oak, then you'll have laths which are over the floor joists. Put 1/4 plywood, then a thinset, then 1/4" Wonderboard (or whatever to meet the desired other flooring height), then mortar and tile. Be sure to use screws to secure the Wonderboard throught to the joists.

You could even remove the laths, then you could nearly match your existing flooring. You'd need minimum 1/2" plywood, and 1/2" Wonderboard.

That would be a rock solid finish.

samurai.

[EXT]

Laths on a floor? Where are you? 1/2" plywood is NOT enough under 1/2" wonderboard, 5/8" minimum for joists on 16" centers. If you need to keep height down, use 1/2" ply over the joists but first put 3/4" between the joists level with the joist top, with 2x2" attached to the joists under the ply, supporting the edges, then install the 1/2" ply subfloor, add the wonderboard then you have a solid base.

[Manster]

The OP said he was screwing the oak to the joists. Anyway, a 1/4" Hardibacker over the oak would give it some density, however ripping it out is overkill and 1/4" plywood is good for cabinet backs, not sub-flooring. Also the Hardi or Wonderboard does not need to be screwed to the joists. Ya want proper? Place an actual mortar bed over the sub-floor for a tile base.

[Mikepier]

What if I used an anti-crack membrane over the oak floor?

[Mikepier]

OK, I think I'm going to tear this floor up and just lay in a 3/4 plywood. I tried taking up some of the floor and it looks like it's coming up easy, so I'll just do it the right way. Thanks for all you inputs.

[Manster]

It would help I'm sure.

Then glue and screw the plywood to the joists, followed by 1/4" Hardibacker over that plywood.

[Mikepier]

I figured it would better to put 3/4" plywood rather than 1/2" plywood plus 1/4" hardibacker, right or wrong?

[Manster]

I suggest the 3/4" ply + the Hardibacker. With the plywood there's chance of flexing, the backerboard adds density which helps to eliminate flex problems. You'll sleep better. :-)

I posted this link the other day. It's a short but IMHO extremely important read. Check it out.

[Mikepier]

I can only go 3/4" high due to height problem matching existing floor. So whats better? A) 3/4" plywood, B) 1/2" ply plus 1/4" backer C) 1/4" ply plus 1/2" backer

[Mikepier]

Forgot to mention I am still keeping my 3/4" subfloor.

[Mikepier]

Looks as if this thread has changed topic, so I'll post this question in a new post.

[Jeff]

You may wish to consider .5" plywood and ditra, this stuff...

[Big_Jake]

See my post. That's exactly what I did over a maple floor.

JK