Mass timber construction relies on encapsulation to protect the wood from water. While wood can get wet for short periods of time, prolonged storage under damp conditions can increase the risk of fungal decay. Effective moisture management during construction and while in service is essential.
To further reduce the risk of decay, FPInnovations staff have explored the efficacy of borate rods and borate glycol formulations for their ability to inhibit decay in mass timber exposed to damp conditions. The combination of these preservatives was associated with reduced incidence of decay after 9 to 12 months. These results suggest potential application in vulnerable areas to further reduced decay risks.
Additional studies have explored the use of a surface-applied borate glycol/DDAC formulation as a remedial preservative to prevent the regrowth of fungi in decayed wood. After six months of exposure, fungal regrowth was significantly reduced or eliminated in treated specimens compared to untreated controls. The results suggest that borate glycol/DDAC may provide additional protection against fungal regrowth, as part of a broader remediation plan.
This research highlights potential pathways to protect and remediate mass timber elements. The products used in these studies are commercially available in Canada. Please check out our full research paper in Wood Material Science & Engineering. https://doi.org/10.1080/17480272.2026.2748937
This project had been made possible by Natural Resources Canada’s (NRCan) Forest Innovation Program and BC’s Forest Innovation Investment.
An untreated control block of CLT showing fungal growth
For more information, please contact
Rod Stirling, Manager, Workforce & Infrastructure
Rod.Stirling@fpinnovations.ca
