As part of our on-going mass timber work, Dr. Gwynne Mhuireach just published a paper entitled, “Effects of wetting events on mass timber surface microbial communities and VOC emissions: Implications for building operation and occupant well-being.” The paper is part of a special collection on Interactions Between Natural and Built Environment Microbiomes in a One Health Context in the peer-reviewed journal Frontiers in Microbiomes. A huge thanks goes out to co-authors Mark Fretz, Elliott Gall, Kevin Van Den Wymelenberg, Jason Stenson, Dale Northcutt, Aurelie Laguerre, Patrick Finn Horve, Leslie Dietz, and Susan Collins.
To summarize the study, we inoculated the surfaces of coated and uncoated cross-laminated timber (CLT) blocks with a mock community of common human-associated microorganisms, placed the blocks inside sealed microcosms, and then used shotgun metagenomic sequencing to characterize changes in the microbial communities over time under both dry and several wetting scenarios. We also measured emission of volatile organic compounds (VOCs) throughout the experiment.
Our main findings were that:
1. Mass timber blocks had lower bacterial abundance than the plastic control for the majority of the study (except at the beginning right after inoculation), but there was no significant difference between coated and uncoated CLT blocks.
2. Generally, coated CLT blocks emitted more VOCs than uncoated blocks. VOCs emitted by coated blocks were more related to industrial solvents and coatings, while those emitted by uncoated blocks were mostly plant metabolites, such as terpenes.
3. Wetting had a significant effect on bacterial community composition, but the effect varied depending on coating status of the CLT blocks.
We extend our gratitude to the US Forest Service for funding this research through the Wood Innovation Grant Program and to our partners at Oregon State University AA “Red” Emmerson Advanced Wood Products Laboratory and Portland State University Healthy Buildings Research Lab. A heartfelt thank you also goes out to our industry collaborators, including ZGF, NBBJ, PAE, Perkins&Will, SRG + CannonDesign, Miller Hull, Scott Edwards Architecture, Ankrom Moisan Swinerton, Providence St. Joseph Health, PeaceHealth, British Columbia Building and Safety Standards Branch, Oregon Department of Forestry, who provided invaluable insight through focus groups, architectural design studio reviews, and other interactions throughout the project.
Read the whole paper here https://www.frontiersin.org/articles/10.3389/frmbi.2025.1395519