The aim of this study is to determine the criteria for the wall structures in cold region where fibrous thermal insulation materials are used, by measuring the hygrothermal condition of the full size specimen wall which modeling the execution defects of thermal insulation and vapor barrier. From the experiment results, the wall with air convection in the cavity has possibility to make condensation at the bottom of the wall. It is clarified that an attic space, wall cavities and a crawl space must be separated to avoid air flow connections among them. Vapor barrier installed continuously, and ventilated air space are also effective to keep from making condensation in the insulated wall cavity.
