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I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values?

April 26, 2017Black integrity lumber mold stress

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I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values?

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No, mold or stain generally does not have an effect on lumber values. It may be a warning flag, however, for high moisture levels, which CAN cause problems. If the moisture content of the lumber is over 19% and stays at this level, two things will happen: lumber strength decreases and decay can begin. If trusses are being designed and manufactured under wet service conditions (over 19% moisture content), then you should check with your plate/software vendor to see if the trusses should be designed as such; even if you expect their moisture levels to drop to below 19% after they are in service. The Western Wood Product Association (www.wwpa.org) publishes a pamphlet called “Unseasoned (Green) Lumber” that discusses moisture and mold in more detail. It’s available as free download in the Technical Publications section of their web site.