mosaic tiling on outside wall

I imagine it could be done the way you do floors, etc. When I used to work
building cabinets, we did a mosaic tile countertop with plywood, but we used
contact cement then grout. The key to the contact cement is to draw out your
pattern on the bare wood, then roll on a thin coat of cement, and let it dry
completely. It shouldn't even be tacky. Then, lightly coat the backs of the
tiles and let them dry, also. Then place them exactly where you want them.
They won't come off if they're in the wrong place, so I don't suggest doing
this after a couple pots of coffee *lol*
Then take something like a rolling pin and roll over the entire surface to
ensure a good bond. Wait 24 hours, then grout as usual! It worked on the
countertop, and is still holding up. Good luck, let me know if you try it.

Marsha