Wall Design Redundancy for Improving the Moisture Performance of Building Cladding Systems in Hot-Humid Climates

Abstract

An investigation of approximately 4,000 buildings in the hot-humid climate locations of the United States where the potential for decay of hygroscopic building materials or corrosion of metals is moderate-to-severe found that redundant moisture barriers are necessary to accommodate statistically probable water leakage in building envelopes. Conversely, the research found that reliance on surfice barrier cladding designs without redundant moisture barriers can lead to water-related problems of rot, corrosion and deterioration. Exterior wall designs that incorporate drainage planes (vented wall designs), rain screens with drainage planes (pressureequalized or ventilated designs), and mass storage systems are better alternatives for building designers to consider in hot-humid climate locations. These failure mechanisms that are prevalent in surface barrier systems are demonstrated from the field research. Ways to reduce the potential for problems caused by water leakage using redundant drainage planes are provided in the paper.