Lumberyard Mold, Blue Stain, Health and Assessment for Remediation

"They" say mold on an attic 2x4 is just lumberyard mold. “They” say it’s not harmful.

REALLY?

QUICK ANSWER:

It is impossible to determine if a mold is “lumberyard”. In fact, the term is too broad and vague to be of any value to assessment or decision-making.

Unfortunately, this vague term is entrenched into the everyday lexicon of the mold remediation industry even though it is neither clearly defined nor used with a consistent meaning.

In addition, it is difficult if not almost impossible to determine if a mold growth in a building does “not present any health issues” by looking at it.

The assessment of health risk from mold growth needs to consider more than just a generic name or its appearance.

THE CLAIM

Someone who claims, “The mold on this two-by-four is just lumberyard mold”, followed by, “Don’t worry about it, lumberyard is not bad”, is affirming, assuming, or outright guessing that:

1.   The mold growth was “caused by some condition at the lumberyard”,

And,

2.   The mold growth is “expected and normal on lumber before it is installed in the building”.

They are ALSO claiming they have full confidence that:

3.   The mold is not hazardous because it is “lumberyard mold”.

This bundle of propositions suggests that a mold species known to cause health effects will not grow BEFOREinstallation, i.e., bad mold does not grow in the realm of the “lumberyard”.

This also means the opposite: “hazardous” species will only grow AFTER the wood is installed.

And finally, it also means the person making the claims are confident that there are actually molds that do not cause health effects and that they know the difference between good mold and bad.

Hopefully it is obvious that this entire scenario is not plausible. And probably negligent.

BLUE STAIN

There is a common mold found on lumber known as “blue stain” or “sap stain”. This is often one of the many visible molds people incorrectly identify as “lumberyard” mold. It is not reported to be hazardous or allergenic.  These species are usually genera Ophiostoma and Grosmannia in phylum Ascomycota.

These molds appear as a faded blue, gray-blue, gray, and sometimes black discoloration embedded in the fibers and have no obvious three-dimensional growth that can be seen or removed (i.e., wiping or scraping will not remove the color). The color is from the pigment found in the filaments.

Recently, some cabinet makers, artisans, and consumers find this staining attractive and have placed increased value upon attractively stained, “denim” colored wood.

Blue Stain mold typically grows immediately and shortly after harvest of the tree, and possibly also during the early first round of milling (i.e., cutting down, removing bark, ripping a round log into square timbers, stacking cut boards, etc.). It is important to note that it grows prior to kiln drying, the heat of which kills both the spores and the growth (air drying will not stop blue stain fungal growth activity). Often blue stain mold infects a living tree and if extreme can contribute to its death.  Because bark beetles spread the spores, they are commonly found together, with the stain predominant in or near the beetle galleries in the wood.

Blue Stain mold growth is not due to wet or damp conditions (aka water damage). It is not a cellulose and lignin destroying mold and causes no structural damage or deterioration of the wood lumber.

Blue Stain or Sap Stain mold is identified and described by the U.S. Forest Service as far back as the early 1900’s.

WATER DAMAGE MOLD

The molds that appear on lumber prior to installation grow during transport, storage, indoors or out, because of wet and damp conditions. Wet and damp conditions also cause damage to components and materials; the industry knows that unattended water damage, leaving materials wet, will cause mold to growth. Hence, “water damage molds” is an acceptable term.

Water damage molds typically grow to be a three-dimensional visible film on the wood surface (or slightly embedded in between loose or separated fibers); they are from many genera and species, including but definitely not limited to Alternaria, Aspergillus, Cladosporium, and Penicillium. Rarely will these growths on lumber be from the Stachybotrys or Chaetomium genera, tertiary colonizers which require much wetter conditions for much longer periods of time.

Perhaps it would serve the industry better if lumberyard mold was renamed. It should be properly recognized and labeled as mold that grew because the wood was wet enough long enough to grow mold. It would be even better if the mold was labelled based on the time period of where the lumber was during its product life cycle when the water damage caused the growth.

The periods of likely growth include:

•    harvest (for the already discussed “blue stain” conditions),

•    transport (bundles on trucks and trains)

•    warehousing (wholesale holding, and point of sale retail locations including “lumberyards”)

•    construction (on-site storage and unprotected building assemblies)

RISK to OCCUPANTS’ HEALTH

It is critical to note that when one is making assumptions or simple risk assessments regarding health impact, there is very little valid information on how to predict which occupant will get which symptom, or how long of an exposure to mold (spores or growth fragments) is needed to cause which symptom. (See also, my other article, “The Seven Health Effects of Mold”, for information useful for assessing exposure and risk.)

Remember that the risk assessment is calculating the “likelihood of harm”. Risk assessment requires information and predictions from the exposure assessment. Exposure assessment therefore must be conducted first. If there is zero exposure, there is zero risk, regardless of the type of mold or health effect.

Thus, when anyone tells me, “This is just lumberyard mold”, I respond, “So?”.

In other words, it would be prudent for the remediator or assessor to consider and adopt the intent of the S520-2015 (and the clarified language of the soon-to-be-released 2023 revision) and either:

“Assume with justification that the growth is a type that is a risk to health”,

or

“Use analytical procedures to confirm if the genus and/or species is a type that would pose a risk (i.e., sample collection and laboratory analysis combined with relevant supporting literature)”.

HOWEVER, for situations similar for the current scenario, a 2x4 in an attic, the location of the mold is also important. If the mold is in an attic or a cavity, the air in that space is unlikely to communicate with the occupied space below or adjacent. An assessment of the building systems and functioning attributes would reveal it is unlikely that a significant measurable exposure of any mold in that compartmentalized attic space would occur to the occupants in adjacent or nearby living spaces.

This means, that mold in the attic, even if “extremely toxic”, would not pose a significant risk to the health of the occupants. However, all buildings can fail and it might be possible to move contamination from the attic to the space below. While this is unlikely, the possibility must be taken into consideration while making the exposure and risk assessments.

DECISION-MAKING TIME

Hence, like any visible mold growth in a building, it is prudent to assume this growth on lumber, errantly called “lumberyard mold”, is one of the nearly countless mold species that have the potential to cause health effects to someone.

The prudent remediator would therefore inform the occupant that a professional exposure and risk assessment be conducted before making decisions to commit resources to remove or keep the mold on that piece of 2x4.

Jan 4, 2023 - J.S.Armour