The Country Club is a circa 1920 mass masonry eight-story building, with exterior walls composed of either brick cladding or stucco rendering over brick, with a hollow terra cotta block backup wall. BSC investigated the blistering of an elastomeric coating which was recently applied to the existing stucco, in an effort to address bulk water intrusion issues. The failure of the elastomeric coating was unexpected, given that it is designed to allow drying (“breathe”), and permit the escape of water. The pattern of the blistering was examined, and correlated with exterior bulk water drainage features, orientation, exposure, and other factors. The likely cause of the blistering was determined as bulk rain water entry at improperly detailed parapet caps, which introduced water into the body of the brick and stucco wall. This rate of water entry was greater than what could dry (by vapor diffusion) through the elastomeric coating, resulting in the observed blistering. BSC recommended several retrofit measures to reduce the bulk water intrusion and accumulation in the parapet wall, which would reduce or eliminate these problems.
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