On Saturday, July 2, 2016 at 10:43:33 PM UTC-4, Ed Pawlowski wrote:
On 7/2/2016 10:04 PM, wrote:

We saw some porcelain tile we liked, but it's ok to use concrete board over OSB? I'm not sure why the Home Depot guy was so insistent that that was a bad idea.

Thanks,

Mike
Because it's a bad idea. Not saying your installation WILL fail, but
the chances of success using OSB will be significantly lower rhan with
plywood - and just putting plywood over the OSB is not quite as
effective as replacing the OSB and doesn't raise the floor level as
much.


I'd talk to a real tile guy, not the Home Depot guy.

Or just google. Did that and there is plenty of information there from
credible sources to figure it out, including this from HD:

"Tip: Make sure the subfloor will not deteriorate when it gets wet. Particleboard is not an acceptable subfloor material for tiling projects. Oriented strand board, or OSB, and exterior-grade plywood will work if first covered with a latex-modified mortar and a tiling backerboard. "

And did he ask the HD tile guy what the specific problem with OSB is?