I have 1 3/4 sheets of exterior insulation covered on felt. I used white felt but have read off white or light gray is good. Attach the felt to the foam board with spray glue starting in the center working toward the ends a section at a time so you can smooth it out before the glue sets.We put it up with L screws. The long leg is threaded and screws right into the wall. Used 4 on the long sides and 3 on the short sides. This means you can turn the screws sideways if you need the board to be portable and have only a few holes to patch if you need to take it down completely.