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 damp-proofing using a degradable asphalt-based covering.
Waterproofing an existing basement begins with excavating to the bottom sides of the footings. Once excavated, the walls are then power washed and allowed to dry. The dry walls are sealed with a waterproofing membrane and new drainage (weeping tiles) are placed at the side of the footing.
Over the past ten years, polymer-based waterproofing products have been developed. Polymer-based products last for the lifetime of the building, and are not affected by soil pH. Polymer-based waterproofing materials have the advantage of a low enough viscosity that they can be sprayed directly onto a wall, are very fast curing, and are semi-flexible, allowing for some movement of the substrate.