In general terms, industry research24 identifies three critical moisture content “thresholds” describing the exponential acceleration of the biodeterioration process:
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20-24% MC = slow growth of previously established rot and mold spores;
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25-29% MC = moderate growth of rot and mold spores; and
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≥ 30% MC = fast growth of rot and mold spores.
Clearly, these threshold levels confirm that even a 10% increase in moisture content may result, over an extended period, in significantly increased mold and rot growth. Considering such potentially acute effects of even small increases in moisture con-
8 • Interface June 2003
tent, a comparative evaluation of the moisture exchange performance of OSB and plywood is warranted to determine if one of the products tends to experience somewhat higher moisture content levels during extended “wet” conditions.