Wood and wood-based products interact with the surrounding environment. The interaction with moisture is particularly interesting since it influences the structural properties and may lead to degradation. A structural health monitoring system was established in House Charlie, a four-story office building in Växjö, Sweden, made from timber. It has been running since summer 2018, collecting vibration data and information on temperature and humidity at multiple positions within the façade and the slab. The present work shows that the moisture content within a slab of the building varies throughout the years, attributed to an ongoing dry-out and seasonal changes. Furthermore, the variation is directly coupled with the weather data from a public weather station in Växjö.