 As a further encapsulation measure, crawl space access doors are sometimes located inside the home, or an airtight, insulated access door is built in the perimeter wall.A crawl space can be susceptible to flooding, a risk that is sometimes mitigated by such measures as using rain drainage such as rain gutters to conduct rainwater away from the house and sloping the earth away from the house.Crawl space wall materials may include, e.g., solid concrete or concrete masonry units.