I recently conducted a mold test at an area gym and the results were jocking, I mean shocking. The first thing I noticed as I entered the large locker room/gym is that it was the coldest indoor room that I have ever been in. I would guess around 65 degrees or so. My client informed me that there was mold growing on top of the ceiling tiles so I checked it out. Sure enough, he was right. I proceeded to investigate various locations throughout the structure totaling about 7 or 8 spots. Every 24 inch ceiling tile was completely saturated on the topside and massive amounts of mold were present. This was more mold than I have ever seen, it was a pretty large building.
Science behind the mold
The large ceiling cavity above the tiles was open to hot humid air from the outside. Open soffit vents surrounded the building. There was 6 inch fiberglass batt insulation on top of the ceiling tiles but of course this is not a vapor barrier. So the humid air was in contact with the topside of the half inch ceiling tiles, which were cool to the touch because of the cold dry air within the gym. Therefore, the tiles were cooling the laminar boundary layer of air right above them to dew point. This depositional process caused dew to form on top of the ceiling tiles, so they were all wet. A perfect environment for mold growth and that was the case. I took an outdoor control air sample and an indoor air sample along with a swab sample from above the tiles and sent them to the laboratory. The results came back with high concentrations of stachybotrys mold. This is the most dangerous type of toxic mold and a huge concern for the owners of the structure as well as the athletes who use the facility.
I recommended professional mold remediation. I think the best recourse for the structure would be to close off all the soffit vents and make the whole attic a conditioned space. There needs to be at least 2 inches of closed cell foam spray between the rafters to supply an adequate thermal break. With a cold gym maybe 3 or 4 inches would be better. All the ceiling tiles, batt insulation and ceiling structure should be thrown away. A whole gym dehumidifier should be added because of the many athletes that sweat profusely as they work out, adding to the relative humidity inside the building. This is going to be a very expensive fix, but my suggestions should take care of the problem.