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In 2017, a moisture monitoring study was initiated on an eight-story, mass timber building located in Portland, Oregon. A detailed description of the monitoring program and initial monitoring results from the first year of the program were published previously. It was discovered that by the end of Year 1, some of the mass timber components had not dried below 19% moisture content (MC). This technical note is a follow-up to the original paper to examine how the building changed over its first 3 years after construction. All of the locations monitored over 3 years have reached stable moisture contents between 10% and 15%, which are acceptable for building functionality and performance. The main conclusion from this study is that mass timber buildings can naturally recover from construction wetting provided that such buildings are properly enclosed and further moisture intrusion is prevented. [ABSTRACT FROM AUTHOR]

The use of mass timber structural products (such as glulam and cross-laminated timber) in commercial buildings is increasing in prevalence around the world. Whereas moisture management during the construction process is important for all building types, it is especially important for buildings with wood structural members. The exposure of mass timber products to the environment during construction can result in wetting of the wood, and mass timber products may take longer to dry than lightweight wood-frame construction. To better understand the moisture conditions to which mass timber framing systems are subjected, a monitoring study was initiated on an 8-story, mass timber framed building located in Portland, Oregon. The study used wireless sensors to continuously monitor moisture content in the wood components over the transportation, construction, and operation of the building for a 1-year period. This study witnessed record levels of rainfall during construction, representing very adverse conditions for mass timber projects. However, the data showed consistent drying of all mass timber products after the completion of the building, with glulam and light framed wood products drying at a faster rate than cross-laminated timber. The method to install the instrumentation was also examined carefully for potential bias, which provided valuable lessons to future on-site moisture monitoring projects. [ABSTRACT FROM AUTHOR]