Hi CLKD, we once built a beautiful home in Alabama (that we had to sell as we spent too much building it) and the contractor insulated between the two floors without leaving an air space. It was not long before I noticed black coming out around the edges of the ceiling vents for the heat/air. Horrible experience.
We have it on our north facing brick - I spray with Clorox to remove it, but I have two air cleaners and a de-humidifier in the house and so far, so good. Nothing in the shpwers - well, maybe a rare spot.
The south has so many beautiful birds, plants and waterways that we'll put up with mold (no u) to enjoy the beauty. In Colorado Rockies, we lived at 7600 ft. elevation and one season had 41 species of birds and our biggest problem was the black bears tearing down the feeders and the suet hangers. In California, where we lived our working years, there were so many homes and buildings and so few trees that the wildlife was a party at a bar - yuk.
However, did decide our block (neighborhood) badly needs the equivalent of a pub. Not much chatting around-lots of retireds. So we are going to build a front courtyard and put benches to see if that perks things up.