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Moisture Uptake Testing for CLT Floor Panels in a Tall Wood Building in Vancouver

https://research.thinkwood.com/en/permalink/catalogue2343
Year of Publication
2017
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Lepage, Robert
Higgins, James
Finch, Graham
Year of Publication
2017
Country of Publication
Canada
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Moisture
Keywords
Water Resistance
Coatings
Hygrothermal Models
Moisture Content
Sensors
Biodegradation
Funghi
Language
English
Conference
Canadian Conference on Building Science and Technology
Research Status
Complete
Summary
Cross laminated timber (CLT) and mass timber construction is a promising structural technology that harnesses the advantageous structural properties of wood combined with renewability and carbon sequestering capacities not readily found in other major structural materials. However, as an organic material, mass timber is susceptible to biodeterioration, and when considered in conjunction with increased use of engineered wood materials, particularly in more extreme environments and exposures, it requires careful assessments to ensure long-term performance. A promising approach towards reducing construction moisture in CLT and other mass timber assemblies is to protect the surfaces with a water-resistant coating. To assess this approach, a calibrated hygrothermal model was developed with small and large scale CLT samples, instrumented with moisture content sensors at different depths, and treated with different types of water resistant coatings exposed to the Vancouver climate. The models were further validated with additional moisture content sensors installed in a mock-up floor structure of an actual CLT building under construction. Biodeterioration studies assessing fungal colonization were undertaken using the modified VTT growth method and a Dose-Response model for decay potential. The research indicates that CLT and mass timber is susceptible to dangerously high moisture contents, particularly when exposed to liquid water in horizontal applications. However, a non-porous, vapour impermeable coating, when applied on dry CLT, appears to significantly reduce the moisture load and effectively eliminate the risk of biodeterioration. This work strongly suggests that future use of CLT consider applications of a protective water-resistant coating at the manufacturing plant to resist construction moisture. The fungal study also highlights the need for a limit state design for biodeterioration to countenance variance between predicted and observed conditions.
Online Access
Free
Resource Link
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