Water Resistance and Durability of Weather-Resistive Barriers

Weather resistive barriers function as the second line of defense against water that has intruded past a building's cladding. Despite its importance, however, the evaluation of weather-resistive barrier water resistance performance is not conducted in a consistent manner across product types. Several different test methods that include vastly different water exposure techniques are used. Because of the variance in test methods and rating systems, the selection of optimal weather resistive barrier for a specific project can be difficult. Complicating matters further, the water resistance of weather resistive barriers is almost always reported on as-received materials, with little if any information provided on how the water resistance will change during the construction period or in service. This paper presents data comparing the water resistance of weather resistive barriers measured by both standard methods and by a small-scale water spray test. Additionally, the change in water resistance performance due to direct environmental exposure is discussed.