Temperature and moisture performance of wall assemblies with fiberglass and cellulose insulation
Rose, W. B. and McCaa, D. J.
1998 Thermal Performance of the Exterior Envelopes of Buildings VII, Clear water Beach, Florida, pp. 133
OSB, field conditions, vapor barrier, mold growth, cavity
Rose, W. B. and McCaa, D. J., (1998), "Temperature and moisture performance of wall assemblies with fiberglass and cellulose insulation", Thermal Performance of the Exterior Envelopes of Buildings VII, Clear water Beach, Florida, pp. 133.
A three-year study in Champaign, Illinois, was designed to measure the thermal and moisture performance of various typical wall assemblies, especially OSB sheathing, under field conditions. The variables that were studied included
insulation material (fiberglass and cellulose), vapor barriers (none, polyethylene, and facing material), encapsulation materials, means of all achment of facing material, and location within the wall cavity.
Measurements of temperature and moisture content, using Duffprobes, were gathered at hourly intervals over three winters, and plugs made of the OSB sheathing material were regularly weighed for gravimettic moisture content measurements. The interior was maintained at constant humidit)?---50% -55 % for one year and 40clo for two subsequent years. FoIlowing the study, the walls were disassembled and inspected for sheathing condition and mold growth.
Two samples with no vapor diffusion protectior4 one cellulose and one fiberglass, showed unacceptably high levels of mold growth. All of the samples with vapor barriers or encapsulation remained at a safe level of moisture content. Some of the samples with encapsulated and faced material showed mold growth at the tops of the cavities, particularly where cabling pierced the interior drywall.
The construction and building pressure management for this study were such that the moisture performance is a consequence of the diffusion capillary regime, not the air leakage regime. The cases that were unacceptably bad in this study were affected by diffusion and capillary moisture, not air leakage, under the interior and exterior loads imposed by the test.