Sto Corp. has passed both air and moisture testing during a recent BEC/BSA 2010 Air Barrier Design Challenge held in late May.

Hosted by Architectural Testing Inc. in Chelmsford, Mass., ten teams of practicing design and construction professionals assembled 4-foot-by-8-foot building envelope mock-up panels with a variety of membrane and fluid-applied air and moisture barrier systems. The Sto team used StoGuard, which was the only product tested that did not leak in both the air and water tests, including at the sensitive material joints or at screw holes, the company reported.

The two testing methods used in the challenge were the ASTM E 783 (field test for air leakage) and the ASTM E 1105 (field test for moisture leakage).

“Even though all the wall assemblies in this test passed the air leakage test, Sto was the only one that had absolutely no moisture leakage,” said Lisa Petsko, Sto product manager for StoGuard. “The challenge results point to the fact that a ‘thicker’ membrane is not always better, meaning that membrane systems that claim the they are more effective because they are thicker (sometimes up to 90 mils), did not perform as well as a fluid-applied system like StoGuard at around 6 mils on the wall. Why pay for more when it is not needed?”