I have vertical OSB skirting attached to a 2x4 frame for a sunken tub surround. We plan on finishing the bathroom with subway tile. Can I adhere the subway tile directly to the OSB, or should overlay cement board first? I've seen many posts about OSB flooring and tiling, and using cement board first, but this OSB has no stress/pressure on it. Or am I still bound by the fact that the two substrates (tile & OSB) have different expansion properties, thus cement board is a must?
Thoughts?
Thoughts?