Mechanical—Not Natural—Drying Is a Must After a Flood

New research reinforces the importance of forced mechanical drying after long-term flooding. Mimicking conditions during and after Hurricane Katrina, researchers from Tuskegee University built, flooded for three weeks, and then dried a home to determine the effects of long-term saturation, natural and mechanical drying, and mold remediation on the building materials.

The results, published in Home Energy magazine, are a follow-up to earlier Tuskegee research on short-term flooding. The earlier findings suggested natural drying is adequate for homes flooded for three days and left sitting for five days, but long-term flooding likely calls for more aggressive action, author and lead researcher Heshmat Aglan, Ph.D., P.E., explains.

The findings provide empirical support for a variety of recommendations for drying and remediation after long-term flooding:

• In the study, natural drying was not effective at reducing building material saturation after three weeks of flooding and three weeks of sitting.
• Mold spores decreased after natural drying began, but forced drying made the process much faster, suggesting the latter is a more effective option after long-term flooding.
• Absorbent furnishings and cabinetry should be removed from the building during drying.
• Paper-faced building materials should be completely replaced after long-term flooding. According to Aglan, the paper facing on fiberglass batts and drywall both continued to show mold growth two years after drying and remediation of the test home.