Full Description

The objective of this project (496-RP) was to continue, as Phase II, the investigation of ASHRAE 337-RP, studying additional aspects of the moisture performance of an insulated wood-frame wall structure. The data developed in this project include: 1. Moisture performance under cyclical (diurnal) shifts through the freezing point in the cold side temperature conditions. 2. Moisture accumulation rate as a function of the amount of accumulated moisture. 3. Water vapor transfer rate of sheathing materials at low temperature. 4. Winter condition moisture accumulation rate with the vapor retarder on the outside of the envelope, as for buildings in a hot/humid climate. 5. Conditions that would create persistent condensation on die inner surface of lap siding over sheathings that are absorptive and virtually non-absorptive. The new data, along with results obtained previously under ASHRAE 337-RP, will supplement the revised information to be published in the Handbook of Fundamentals as "Thermal Insulation and Water Vapor Retarders," and "Moisture in Building Construction." The data will indicate situations for which data are needed to minimize moisture problems in construction.