What the Heck Happened, A Case Study in a New Building’s Stucco Gone Wrong

A recently constructed charter elementary school had a huge problem. Their new stucco of about 8 years was extensively cracked and the window perimeters were leaking into the classrooms. This case study will address the steps of investigation which included forensic discovery of the extent of the problems and the resultant decomposition damage and insect infestation which occurred due to the problem water infiltration. This will then address the assessment that the originally designed traditional three-coat stucco, was mis-applied. Instead of applying the required second or brown coat, the problem assembly jumped ahead and installed an extra-thick finish coat. This then caused excessive shrinkage, extensive spider cracking, and complete delamination of the finish coat from the stucco backup scratch coat. The cracks and the delamination allowed the free-flow of wind-driven rain to travel past the mis-flashed windows and into the children’s classrooms. To remove and reinstall traditional three-coat stucco with a color finish would not have fit into the summer construction schedule, so instead, a drainage back, direct-apply, DEFS to cement board stucco system, along with new flashings and fluid-applied air and weather barrier was selected. This allowed the entire remediation project to occur within the summer construction season prior to the start of school. The result is a water-tight project, that looks exactly like the original stucco intent, but now is even better with reliable back-drainage, flashings, and of-course without the plaguing problems.

Learning Objectives:

1. Review the guidelines for traditional three-coat stucco.
2. Describe why too much of the stucco finish coat may cause a problem.
3. Clarify why flashings are needed at windows instead of relying on the integrity of the finish materials.
4. Contrast the differences between three-coat stucco, EIFS, and DEFS hard-coat to cement board systems.

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George David Schoenhard, AIA, ABAA, REWC, BECxA, RRO, CSI, LEED AP, OSHA, Manager & Principal, Design Support Services of Philadelphia, LLC (DSS-Philly)

George David Schoenhard, AIA has over 45 years’ experience in designing fine architecture, with the last nine as the Principal of DSS-Philly, one of the leading High-Performance Building Enclosure consulting firms in the Philadelphia region. He brings his decades of architectural experience to skillfully advise and design, implement or remediate building enclosures on behalf of other architects, owners and contractors. He is the inventor and developer of the high-performance Back-Lattice Wall Design. He actively researches comparative building enclosure assemblies, speaks nationally, presents ABAA Webinar’s, and is an AIA Continuing Education Provider.