The current standards need more specific serviceability criteria for Cross-Laminated Timber (CLT) floors since in some cases discrepancies can be observed between the floor in-service performance in reality and those predicted in standards and design codes. This paper presents a series of analyses of a case study in Sweden, which presented higher fundamental frequency in the CLT floors than predicted in Eurocode 5 (EC5). It aims to investigate the effect of non-structural walls on the floor modal parameters through experimental measurements. The authors compared the analytical predictions of the fundamental frequency using the new draft version of EC5 against the corresponding experimental estimations. Using a sensor-roving approach, a dense sensor configuration was adopted to identify the three floors’ modal parameters. Then, different human-induced excitation scenarios were performed to analyze the floor dynamic responses. The results and analysis in this study shed light on the significance of non-structural internal walls on the vibration performance of the CLT floors, a factor not considered in the practical design for serviceability verifications. The study shows that the presence of partition walls can provide a higher stiffness leading to a significant increase in the first fundamental frequency.