This is a crawl space had significant mold issues due to high humidity levels. This was due to the characteristics of a typical open vented crawl space. Moisture gets caught in the crawl space through airflow patterns. When the moist warm air meets the cool surface of the wood framing and on the HVAC ductwork, mold starts to grow quickly. Sealing off the crawl space and installing a proper crawl space dehumidifier is the only way to take care of this design flaw permanently. Luckily, this homeowner will not have to worry about their home rotting away from the bottom up now.