Results of a Water Vapor Transmission Round-Robin Test Using Cup Methods

Ten institutes and laboratories from the Nordic countries participated in the round-robin test. The materials used were 12-mm porous board, 40-μm polyethylene foil, and 0.8-mm tarred paper. The measurements were performed both as wet-cup tests and as dry-cup tests. The round-robin test shows that the uncertainty of the measurements is considerably larger than the variations of the water vapor resistance (WVR) among the individual test specimens. It is also shown that the test results were greatly influenced by the moisture levels. The results show about 15% gross errors in the test.