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".
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.
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.
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.
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"
That would be a rock solid finish.
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.
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.
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
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.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.