Effect of orientation and slope on hygrothermal behavior of roof assembled with selected components on its hygrothermal response was investigated using a common software tool. Simulations were performed for eight types of roof facing four principle directions, north, east, south and west. The slope of roof varied by step of 15 degrees' from 15 to 45. The hygrothermal response was simulated for a period of two years in a French climate. The weather for this study was generated using a weather generator software. Maximum moisture content in the different components of each roof type, were compared. In this study, the roof type where both sides of the thermal insulation are covered with smart vapor retarders is recommended. (c) 2004 Elsevier Ltd. All rights reserved.