SEDL / STP / STP1352-EB / STP13338S

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

McGinley, WM
Associate Professor, North Carolina A & T State University, Greensboro, NC

van der Hoeven, RSK
Staff Engineer, Atkinson-Noland and Associates Inc., Boulder, CO

Pages: 16    Published: Jan 1999

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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.