We have a concrete patio behind our house(abutting it) and we'd like to put bluestone over it. My husband insists that he can just lay the bluestone on it and put stonedust in the cracks. He says he doesn't even need to adhere the bluestone do the existing concrete patio and it will just stay in place. This seems like it would create water drainage problems and will not stay in place. Wouldn't it be better to put concrete between the stones after somehow adhereing them to the concrete? I'm looking for the steps to do it correctly.