THE MOISTURE PERFORMANCE OF ANY BUILDING is dependent on the outdoor environment to which it is exposed, the indoor environment within the building, and the materials and methods used in its construction. The outdoor environment is characteristically variable, while the indoor environment is under some degree of control and is relatively constant. The moisture performance of the materials involved relate to their physical and chemical properties with respect to the variations in temperature, air, and moisture conditions to which they are exposed, further influenced by the condensation and evaporation of water vapor and the freezing, melting, and flow of liquid water.