The next stop on our crawlspace mold tour is the wooden subfloor joists. These joists are often the first place that you see mold growth because the air from outside is being drawn up through the rest of the house due to air pressure. This phenomenon is called "the stack effect" and it tells us that the air you breathe in your home is drawn up from your lowest level--in this case, the crawlspace. You can find out more about creating healthy crawlspaces by contacting us for our FREE Crawlspace Science book.