The moisture and thermal performance of a typical insulated wood-framed residential wall structure was investigated in the laboratory. The study included the effects of three types of vapor retarder systems and the effects of zero, positive, and negative total pressure differences across the wall. Exposure conditions were representative of a northern winter climate.

Three types of vapor retarder systems were included in the study: polyethylene film ("excellent"), flat latex paint ("poor"), and polyethylene film plus an electrical receptacle ("point-source defect"). The effects of air infiltration and exfiltration were investigated by imposing various negative and positive pressure differences on the wall structure.

Overall time rates of moisture gain (or loss) were measured by weighing the test wall structure daily. Periodically the test wall was disassembled and the amount and location of the accumulated moisture determined. Thermal performance changes were measured by observing changes in the temperature gradient through the insulation layers.

Units: Dual