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Building Basics
Concrete in Foundation Walls is Damp-Proofed and Waterproofed


After the final grade is sloped away from the home, the exterior of foundation walls needs to be damp-proofed and waterproofed to protect the foundation.


Porous concrete foundations should be treated to avoid water seepage into the home as well as very costly repairs. This step is part of a comprehensive set of measures that minimize the risk of water damage.

  • Treat below-grade walls with a damp-proof coating such as an asphalt emulsion
  • A plastic drainage plane may be used instead of (or in combination with) the damp-proof coating
  • Join the surface coating with a layer of insulation—preferably rigid fiberglass or rigid polyurethane foam rated for soil contact
  • Add a gravel layer to provide a good backfill for draining and allow water to flow toward the foundation footing where a perforated drain pipe will carry it away from the structure