Exterior waterproofing prevents water from entering foundation walls
therefore preventing the wicking and molding of building materials.
Waterproofing a structure from the exterior is the only method the IBC
(International Building Code) recognizes as adequate to prevent
structural damage caused by water intrusion. Prior to the 1980s much of
the original exterior waterproofing was actually damp-proofing using a degradable asphalt-based covering.