I seem to recall that it needs something like 30% moisture and oxygen. As a liability issue you really should have the homeowner call a catastrophic cleanup company and have them clean and disinfect it. I'd hate for you to think it's dealt with then 2-3 years from now find out that black mold has bloomed in the whole wall and someone is claiming a health issue.

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2002 Ford ZX2
2 x 2013 Honda Civics