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 the deterioration of structural members. Such
provisions shall consist of maintaining openings in foundation walls,
providing adequate circulation of air in the crawl space, covering
the ground in the crawl space with a moisture barrier, installing
drains outside the structure if the crawl space is below the surrounding
grade, blocking openings in stud walls to prevent the 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.