Moisture Accumulation in Cellulose Insulation Caused by Air Leakage in Flat Wood Frame Roofs

The hygrothermal performance of assemblies can be assessed by testing and monitoring large-scale specimens exposed to realistic conditions under controlled laboratory settings. Moisture transfer cannot be measured directly, but moisture content can be monitored. A large-scale test of two flat roof assemblies filled with cellulose insulation is performed. The six-and-a-half-month test simulated a complete wetting and drying cycle from winter to summer. The wood structure and the cellulose insulation are the object of an extensive moisture content monitoring which included 102 resistance-type electronic moisture probes and 120 gravimetric specimens. The objective of this paper is to report on the changes in moisture content in the cellulose insulation as a function of the different air leakage paths.