At what moisture content (MC) of wood does microbial growth virtually stop?

Microbial growth in wood is significantly impacted by the moisture content (MC) of the material. When wood reaches a moisture content of around 20%, it is generally wet enough to support the growth of mold and other microorganisms. As the moisture content decreases, the conditions become less favorable for microbial activity.

At a moisture content of 17%, although growth may still occur under certain conditions, the likelihood of significant microbial proliferation decreases. However, the threshold for halting almost all microbial activity is generally recognized at around 15%. Below this level, the wood is too dry to support most mold species effectively, thus leading to a substantial reduction in the potential for mold growth.

The concentration of moisture not only influences mold growth but also affects the structural integrity and longevity of wood materials. Understanding these thresholds is essential in mold inspection and remediation processes, where controlling moisture levels can prevent mold infestations.