Damp proofing

Damp proofing in construction is a type of moisture control applied to building walls and floors to prevent moisture from passing into the interior spaces. Dampness problems are among the most frequent problems encountered in residences.

Damp proofing is defined by the American Society for Testing and Materials (ASTM) as a material that resists the passage of water with no hydrostatic pressure. Waterproof is defined by the ASTM as a treatment that resists the passage of water under pressure. Generally, damp proofing keeps exterior moisture from entering a building; vapor barriers, a separate category, keep interior moisture from getting into walls. Moisture resistance is not necessarily absolute; it is usually stated in terms of acceptable limits based on engineering tolerances and a specific test method.