Foundation waterproofing & damp proofing are often confused with one another. Damp proofing is a process which slows down water penetration into foundations where as waterproofing compounds are designed to stop water infiltration.
Damp proofing is usually performed by applying unmodified asphalt coatings to the foundation
surfaces. Most of these products become brittle when dry. Some of them can actually be
dissolved by ground water. Virtually none of them have the ability to bridge foundation cracks.
However, damp proofing compounds are generally very effective in stopping water vapor transmission. Untreated concrete or other masonry products readily absorb water from the soil around your house.
This water travels through the concrete and evaporates from the inside surface of the basement wall. Frequently the walls will appear dry, however, the water is still being transmitted into your
basement. Unless a water vapor barrier was installed beneath your floor, this same thing is
happening with your basement concrete slab.The widespread use of damp proofing methods
did not begin until the 1950's so that's why older houses frequently have "damp" feeling basements.