Tiling over exterior plywood

Leisu

17 years ago

I've been reading that it's okay to tile over exterior plywood

(we have torn up our kichen floor to 2 layers of old wood right now, 100 yold house)

i'd like to just shim some 3/4" exterior plywood on top of that and tile it, is this possible???

Comments (3)

manhattan42
17 years ago
No wood product is an acceptable base for ceramic tile because it swells with humidity changes and this movement will eventually break the bond of the tile to mortar to substrate.

You need to either install concrete back board or pour a mortar base 1" or more thick over your existing wood subfloors before installing ceramic tile.
Leisu
Original Author
17 years ago
How could i pour a mortar base over pine boards? lay a sheet of plastic down i guess....
never heard of this option, would it be cheaper than doing plywood plus backerboard? probably not easier though....
hmmmm.

it sounds like a lot of people do exterior grade plywood in a dry room, guessing the kitchen gets mopped to much for that though.
bill_vincent
17 years ago
How I missed this thread, I don't know. Probably because I haven't spent as much time in the remodeling forum as I used to, but this thread came up in a search someone did, which brought them to my site, and I wanted to clear up some misinformation. The folloiwing is copied and pasted directly from my site's flooring page (linked below):

"Actually, you can[tile over plywood]. I tile over plywood subfloors on a constant basis, both with ceramic, as well as natural stone tile (see pictures 2 & 3). However, because of seasonal movement, as well as how easily plywood can be affected by moisture, it's a risky installation method, if you're not sure of what you're doing. There are alot of additional specs you MUST adhere to when putting together a plywood subfloor, and even the slightest oversight could cause a major problem in the not too distant future. For more information, read this ARTICLE . One common misconception concerning tiling over plywood is that you can use any latex modified thinset (a portland cement based thinset that already has dry latex added to it, and gets mixed with water). After all, it says on the side of the bag you can use it, so can't you? The short answer is yes, but don't expect the tile to last more than a year or two, at best (and before you email me, yes, there ARE exceptions, but generally speaking they won't last). In order to have a good long lasting installation, it's imperative that a quality unmodified thinset be used and mixed with a latex additive. This will give you a higher latex content, and as a result, a stronger bond (see picture #1). In the end, you have a long lasting, beautiful floor."

For those pros who say it can't be done, cheack the TCA Handbook, F-149.

Here is a link that might be useful: My floor tile page