Essentially all materials exposed in conditions conducive to the development of surface mold can over time develop such mold growth. In the vast majority of cases the mold remains invisible to the naked eye, and also insignificant as an issue. However, carbohydrate containing materials, which can provide a ready food source for molds, can under some circumstances be quite suspectible to unsightly mold development during their service life. Such materials can include wood-based products.
As building practices evolve, and the desire for improved energy efficiency in structures has increased, in some cases conditions for mold growth have been enhanced also, usually unwittingly. Incorrect use and/or installation of building envelopes has been a significant contributor in this regard. While treated wood products are not usually an issue in such problems, associated wood or wood fiber based panel products have encountered issues at times. While the best control methods is to prevent moisture conditions conducive to mold growth in the first place, this does not always occur.
This potential for mold growth inside structures has led to the development of methods for simulating and quantifying mold growth potential of treated materials relative to known controls.
Standardized versions of this concept are available as ASTM Standard D4445 and AWPA Standard E24 (available from the AWPA).