Tile over Hardwood

[Bud Cline]

INSTALLING CERAMIC AND STONE TILE OVER HARDWOOD -
NOT THE BEST IDEA!

Hardwood floors have been around for a long long time and under most circumstances have been considered to be stable in most cases, until you add some moisture. Ambient moisture as in humidity occurs 24/7/365. This moisture has an effect on the stability of the wood. Various wood species have varying rates of expansion and contraction. These floor components do move regularly. This movement goes unnoticed and is an acceptable behavior of the species when the intended finished floor is the wood. No one gives this a second thought.

Flood that same wood species with water and watch what happens, again at varying rates. In some cases the wood floor will erupt and never return to its original location. In some cases the wood will cup or crown depending on the occurrence and direction and makeup of the grain, and may or may not return to its original shape. In both cases these are natural phenomenons that occur in all species.

NOW, assume that that wood floor has served it usefulness over time and the time has arrived for a new floor. The natural path-of-least-resistance would be to cover that floor with the new product.

Should one desire to cover THAT wood floor with a ceramic or stone tile installation that is in and of itself a very rigid and non-forgiving application then disaster awaits the unwary doer.

The slightest movement from expansion or contraction would be enough to disrupt the rigid tile installation and the floor would then be doomed. If the underlying wood were to be somehow soaked with moisture the results and effects on the tile installation could be explosive. At the very least adhesive failures could take place dislodging tiles, tiles could crack and cement grouts would crumble. At any rate the tile installation would be ruined.

To cover the hardwood with a substantial amount of plywood may help redirect and redistribute the forces at hand but there are no guarantees. To cover the hardwood with only a cement board product would have no effect on the impending upheaval what so ever. Cement board offers absolutely no structural value (or rigidity) and would in fact be very flexible under such circumstances.

The only way to guarantee a long lasting tile installation would be to remove the hardwood totally and begin anew as prescribed by (among other sources) The Tile Council of North America's "Handbook for the Installation of Ceramic Tile".

In the future one saving-grace may be the use of some of the new so-called flexible thinset mortars coming on the market but even then those products have their limits. There is some protection laterally but if the underlying expanding movement is upward the tile is still doomed.

-Bud Cline
c.

[Daniel Wachtel]

this looked like a good thread to make a "sticky"

[Bud Cline]

This subject came up on a DIY forum at another website and the inquirer was convinced that he/she could install his/her tile directly to his/her hardwood or at the very least cover it with 1/4" Hardibacker. So after composing the above as a message to him/her I thought I would save it "here" for now and expand on it when time allowed. The sticky was a good idea.

This topic is one of many many maverick do's and dont's that exist these days in the wonderful world of tile. Can't find much written about it as far as industry standards and no body seems to want to commit themselves to authoring a "This Is The Way It Is" standard. It's kinda like the ole "Tile Over Vinyl" thing and "shower walls made of greenboard".

[Nick Arrera]

Good tip Bud , I would have put plywood over the wood ..

[Lo Down]

How about installing the Hardi at a 45 degree angle so the floor boards have less effect on the Hardi joints?
No, I'd still say tear the boards out and do it right, but just pondering how to minimize tile movement at the Hardi joints if the wood flooring would actually be left in place.

[cproader]

Alright, I have felt guilty long enough. Here is my confession. Installed 12 porcelain directly over hardwood about two years ago because the huge antique door on this 100 yr old house wouldn't clear with backer board, and they didn't want to pay to have the hardwood removed. So I stuck 'er down with Lat 255 Mukti-Max and used Spectra grout. I walk on it regularly cause it is in my girlfriends music instructors house. She's holdin up fantastic, and there aint a crack in it anywhere. Now granted it is only a 5x6 entry, and I don't feel real good about myself fer doin it, but hey it worked.

This is only a confeesion. Had this been an unpardonable sin, I would not have admitted it.

[Lo Down]

Originally Posted by cproader walk on it regularly cause it is in my girlfriends music instructors house. She's holdin up fantastic................... This is only a confession. Had this been an unpardonable sin, I would not have admitted it.

............. uhummmmm, elaborate.
(caution, some portions may have been taken out of context accidentally.)