SINCE MOISTURE IS PRESENT to a greater or lesser degree in all climates and because it has been shown to be a factor in most deterioration processes in building materials, it is important that building designers and builders take moisture problems into account in the design and construction of buildings. Also, the moisture content of indoor air has a significant effect on the comfort of building occupants, on the properties of various materials, and on the effectiveness of many material-processing techniques. Therefore, control of moisture transfer processes is an important design consideration for buildings. Furthermore, the control of moisture in buildings can have a significant effect on the energy use [1] of a building and on its initial and maintenance cost.