I am redoing two bathrooms on the second story of my home. My husband is very concerned about putting ceramic or porcelain tile over a wood subfloor thinking it will or the grout will crack in no time. Any thoughts or suggestions?
He is right to be concerned. A wood floor will wick out lots of the moisture in thinset, causing it to become a dryer mix than can pop the tile loose.
Install some form of tile backer material on top of the wooden subfloor. This can be 1/4" or 1/2" concrete board or a Kerdi subfloor liner. These liners will isolate wood subfloor movements from the tile and also provide a perfect surface for the tile to bond to.
With concrete backerboard the ceramic or porcelain should work (assuming floor joists and subfloor are adequate). I did this ten years ago and no problems.
For general message board help, click the tab labeled "Tools," and choose "Help" from the dropdown menu.