The exterior of my home is stucco, which has flat, raised areas around the doors and windows. I would like to apply decorative tile (haven't decided whether to use whole tiles or broken pieces in mosaic fashion) to these raised areas. I am in the desert, so the exterior is extremely hot in the summer and sometimes below freezing in the winter. What type of mastic and grout should I use? Does the stucco require any special preparation other than washing off dirt and loose concrete?