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.