Crawl spaces. Crawl spaces shall be maintained free of
moisture, and the flow of air from such spaces into walls above shall be effectively
barred so as to prevent deterioration of structural members. Such provisions
shall consist of maintenance of openings in foundation walls to provide adequate
circulation of air in the crawl space, covering the ground in the crawl space
with a moisture barrier, installation of drains outside the structure if the
crawl space is below surrounding grade, blocking openings in stud walls to
prevent flow of air and moisture into walls, frequent destruction of termite
tubes from the soil to wood floor members above, poison treatment of soil
and other suitable means.