To limit the probability of inadequate moisture resistance or inadequate provision for drying, which could lead to extended exposure to surface water or to water from the ground transferred through masonry or concrete, which could lead to wood decay, which could lead to an inability to resist expected gravity or lateral loads, which could lead to excessive movement, deflection or deformation.
This is to limit the probability of compromised structural integrity, which could lead to:
This is to limit the probability of harm to persons.