I'd like to put Diamond Nitro rolls on a 2-1/2car garage, but concerned about the possible seams seeping water underneath the rolls. Would that be a breeding ground for mold or any other issue that may cause?

To help prevent seepage of water or other liquids under our Diamond Nitro Rolls, we recommend installing the rolls with an overlap seam. You will just overlap on roll over the other about 6" along the length of the two rolls.