Unwanted moisture in concrete floors causes millions of dollars in damage to buildings annually in the United States. Problems from excessive moisture include deterioration and debonding of floor coverings, trip-and-fall hazards, microbial growth leading to reduced indoor air quality, staining and deterioration of building finishes. Understanding moisture in concrete leads to design of floors and flooring systems that provide excellent service for many years. This publication discusses sources of moisture, drying of concrete, methods of measuring moisture, construction practices, specifications, and responsibilities for successful floor projects. The second edition incorporates a brief discussion of terrazzo issues, additional references on drying times of lightweight concrete, an extended discussion of issues with ASTM F1869 moisture emission testing, and updates to the sources of supplies and standards.

Abstract: Two fundamental concepts permeate this writing: the floor is part of a building envelope, but also is in itself a system comprising many elements. For a floor to function successfully, specifiers, builders, owners, and finish flooring installers all must understand the factors for floor performance, especially moisture. In the past few years since the first edition appeared, we have been gratified to see significantly increased dialogue between general contractors, construction managers, concrete contractors, flooring installers, and design professionals. New and improved products have been introduced including flooring adhesives, vapor retarders, and moisture suppression coatings. New moisture test instruments are on the market due to the widespread adoption of relative humidity testing. Use of blotter/cushion layer above vapor retarders in new slabs-on-grade construction has been essentially eliminated resulting in fewer chronic problems with such slabs. However, moisture problems persist due to schedule demands, increased awareness of moisture issues, and sensitivity of some finish flooring systems. 172pp.