When wood, processed for building materials in properties, is sourced, sugars and a multitude of other nutrients are exposed for an optimized site for fungi to colonize. Often, in a property, especially in areas such as crawlspaces or attics, inspectors will come across this fungi; known as 'lumberyard mold'. Lumberyard mold is generally found on new construction materials, and the term 'Lumberyard mold' can refer to a group of molds which are known to be present on these materials.
It is during these instances that it is ideal to perform a swab test on the growth to determine whether it is lumberyard mold or not; since lumberyard mold would be considered 'benign'. From this diagnosis, it could be extrapolated whether or not remediation may be needed in the property, depending on the square footage of the growth in the first place.
Such examples of these types of fungi include both Ceratocystis and Ophiostoma. These types of mold are not generally associated with any particular moisture problems in a property, and are, in fact, usually present on the building materials prior to construction.
Furthermore, when it comes to the byproducts of these molds, no mycotoxins (the metabolic production from molds which cause allergy-type symptoms), have been documented or reported.
It is worth being mindful of another type of somewhat common mold documented on building materials, and is considered a "lumberyard mold", which is Basidiomycetes. Basidiomycetes are generally white in color and can penetrate through the wood tissue, compromising the wood and structural integrity of an area.
Another thing to be mindful of when it comes to Lumberyard mold are secondary colonizers i.e. other molds, such as Aspergillus, which can compromise the air quality, which can colonize the area alongside the Lumberyard mold.
Ultimately, due to the plethora of genera potentially present in an area, it is advised to have the surface growth tested to determine the correct course of action if the area affected is great enough.
Thadigiri, F. (2009) Lumberyard Mold and Sap Stain. The Environmental Reporter. Volume 7, Issue 5. https://www.emlab.com/s/sampling/env-report-05-2009.html
MOLD HEALTH EFFECTS BLOG AND RESEARCH