Gypsum wallboard with repeated or prolonged exposure to water or excess moisture can lose its structural integrity and provide a growth medium for biological contaminants. Poorly sealed buildings, leaking or failed plumbing systems, or improperly constructed HVAC systems can all contribute to water and moisture problems. Gypsum wallboard readily absorbs moisture through direct contact with standing water and differences in water vapor pressure. Regular gypsum wallboard sample sections were hung vertically and exposed to a continuous source of standing water 1.3 cm in depth. Both water absorption (measured in percent moisture content) and vertical movement (wicking height) were monitored within the wallboard over several days. The moisture content measurements revealed a water movement pattern similar to paper chromatography. A leading edge of relative high percent moisture content (～ 20%MC) moved upward along the width of the wallboard. The immersed portion of the wallboard maintained a moisture content level ≥ 20%. Between the leading edge and immersed portion of the wallboard was an area of moderate moisture content (～ 12%MC). Water wicked to a height of 15 cm within the first three hours of testing after which the rate continued asymptotically appearing to reach a maximum height by day 16.
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