This contribution briefly reports some preliminary investigations on the dynamic identifications of an eight-storey cross-laminated timber (CLT) building. Focusing on the vibrational behaviour of mid-to high-rise timber buildings, the Authors aim to study a field that remains largely under-explored despite the increasing use of CLT in construction. Utilising in situ tests from a permanently installed Structural Health Monitoring (SHM) apparatus, the modal parameters of the target structure have been identified over a prolonged period. These include mode shapes, natural frequencies, and damping factors of the building located in Ås, Norway. In particular, this study reveals how the identified modal parameters are extensively affected by the time-varying moisture content of the building material, linking them with the atmospheric relative humidity – an environmental factor which is generally negligible in other contexts with other structural materials. Hence, the research underscores the importance of assessing and compensating for this confounding influence to properly detect structural damage. This would enhance vibration-based SHM through frequency analysis in CLT residential buildings and using data-driven, unsupervised predictive models for the long-term health monitoring of timber structures in variable climates.