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Buildings that leak only on sunny days: Case study and investigative guidelines

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Abstract
This paper introduces a vacant 3,500 square foot electronics manufacturing space in the San Francisco Bay metropolitan area that has sat empty since its construction in 2004 due to sporadic afternoon hot-weather “leakage” from the bottom side of the engineered wood roof deck and associated steel supports. This puzzling phenomenon had been investigated unsuccessfully, first by the building’s developer, general contractor and roofer; and then by an intermittent series of engineers and other consultants. In 2008, the author’s evaluation of data from humidity/temperature loggers installed within the facility confirmed the daily midday appearance of elevated concentrations of water vapor. Further analysis indicated these daily “waves” of ambient vapor were caused by solar heating of water reservoir(s) residing at the building envelope or its surrounds. Upon additional review, both the general location of this moisture pool and the most likely process by which solar-driven vapor caused condensation at the ceiling were reported to the owners. This paper summarizes the forensic-survey process and recommends “investigative guidelines” for similar investigations.
Date
3/2010
Author(s)
Lonnie Haughton
Page(s)
101-119
Keyword(s)
hot weather leak; water vapor; solar heating


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