Assessment of Water Damage in a Mass Masonry Wall Building

Following a modernization and expansion project of a historic school building constructed in 1927, facility personnel observed that moisture damage to interior finishes at the west wall of an auditorium had become more prominent. Damage was most evident in the cement plaster interior finish that had been applied to the interior surface of the exterior brick masonry mass wall. A comprehensive assessment of the mass wall assembly was performed to evaluate potential sources of moisture infiltration. This included a visual assessment of the exterior surface of the wall, which identified various distress conditions such as mortar joint cracks and cracked brick units as probable contributors to the interior moisture damage. In order to thoroughly evaluate other possible factors, an investigation was performed to assess the probability of vapor-driven moisture accumulation in the mass wall contributing to the moisture-related damage. The investigation included long-term monitoring of the interior environment with data loggers and hygrothermal modeling using the measured data to analyze the one-dimensional heat and moisture transfer behavior of the wall assembly. The hygrothermal analysis indicated it was unlikely that vapor-driven moisture accumulation would occur within the wall assembly to an extent necessary to contribute to the observed distress. Water penetration tests of the existing wall assembly and a mock-up of the repointed wall assembly in accordance with ASTM C1601, Standard Test Method for Field Determination of Water Penetration of Masonry Wall Surfaces, confirmed that repointing of mortar joints would significantly improve the water penetration resistance of the wall. Repair documents were prepared to address the conditions found to be contributing to the interior damage.