A question about the hearth flashing. The directions call for aluminum flashing. My experience with construction is that aluminum is generally not used with concrete pours because the chemicals in concrete eat up the aluminum. My thinking is that since all we are trying to do is to isolate the hearth from the stand that maybe a sacrificial barrier may be just fine. On the other hand if the idea is to give an actual slip plane maybe we should use a stainless steel flashing (which would be a lot more expensive) or galvanized steel. Either of these would probably hold up a lot better than aluminum. Any insights?