Environmental response of a CLT floor panel: Lessons for moisture management and monitoring of mass timber buildings

Cross-laminated timber (CLT) is becoming increasingly adopted into North American construction, yet little is known about the impacts of environmental exposure (e.g., to rain during construction) on its long-term performance. The lack of protocols for on-site moisture protection in North America makes it a pressing matter to determine general moisture responses of this material in order to establish a behavioral baseline for practitioners and future researchers. A CLT floor panel sample was exposed to cycles of wetting and drying in an environmental chamber. During these cycles, physical and geometrical properties of the panel were monitored. Testing results indicate that discontinuities in the layup CLT affects the hygroscopic behavior of the product. While the panel showed high dimensional stability, it also exhibited checking, cupping, and interfacial shearing after cycling. Bending test results before and after cycling indicated a reduction of the structural capacity due to the weathering.