Envelope Analysis of Exterior Load Bearing Single-Wythe Partially Reinforced Hollow Clay Masonry Wall Systems for Residential Applications

Abstract

An investigation was conducted to evaluate the movement of water vapor and liquid water (permeance from driving rain), and their effect on the transient moisture characteristics exhibited by single-wythe residential clay masonry exterior load-bearing wall systems. The wall system evaluated was constructed of standard 6 in. hollow (ASTM C 652) units and used a variety of insulation configurations. These wall systems were evaluated for water penetration performance using ASTM E 514 water penetration tests. The transient thermal and vapor transmission characteristics of each configuration were also evaluated using a one-dimensional finite difference analysis (the MOIST analysis program). The results of this investigation indicate that if properly designed and constructed, the wall system provides excellent resistance to wind-driven rain. However, the investigation also indicated that interstitial condensation may occur in the insulation and interior sheathing layers if the system is not properly designed for the prevailing climate.