Volume 6, Issue 9 (October 2009)
A New Testing Method to Evaluate the Relative Drying Performance of Different Building Envelope Systems Using Water Trays in Stud Cavities as Moisture Source
Due to defects in construction, design, and/or deterioration during operation, failure occurs where rain water penetrates into stud cavities of wall systems. Some wall systems tolerate this water intrusion better than others. A new test method has been developed to evaluate the relative capacities of different wall systems to dry out the invading water. In the test setup, the walls of a two-story test hut were made up of 31 wall assemblies (each 2.44×0.76 m2) of different configurations. The hut was erected within a large climatic chamber and subjected to a steady-state climatic loading for 288 days. Within each stud cavity, a water tray on an electronic load cell was placed on the bottom plate to provide a moisture source that represents water penetrating into the stud cavity and provides a consistent moisture loading from one specimen to another. Each wall assembly was instrumented with 25 gravimetric samples and relative humidity and temperature sensors/probes. Indexes were developed to indicate the relative performance of the walls.