In this month's home inspection picture, we see a good example of some typical moisture and moldy growth on a block foundation wall. Whether in a crawlspace or in a basement, block foundation walls tend to be sponges. They draw in the moisture from the ground outside and encourages mold growth. In addition to that, condensation plays a big role. As the ground temperature is colder than the inside temperature (generally) then condensation builds up. A good moisture control system and dehumidifiers can help control this situation.
English, Certified Professional Home Inspector