MOIST (Release 3.0) IS A USER-FRIENDLY PERSONAL COMPUTER PROGRAM that predicts the one-dimensional transfer of heat and moisture in walls, cathedral ceilings, and low-slope roof constructions [1]. It was developed at the National Institute of Standards and Technology (NIST) and released into the public domain in January 1998. It predicts the temperature and moisture content of each of the construction layers, or the relative humidity at the construction layer surfaces, as well as the moisture and heat transfer fluxes at both the interior and exterior boundaries of the construction, as a function of the time of year. The model also can be used to predict annual variations in indoor relative humidity.