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.