I would like to tile our outdoor concrete patio with porcelain tiles and would like advice on how to prepair the concrete. The patio is broom finished. Do I need a crack isolation membrane(CIM)? What is a good CIM, are they all the same? Any additives needed for the thinset? What would the best grout be for this type of application? We live in Minnesota so I want to make sure what we use will stand up to the temperature changes.