Historical structures are increasingly being repurposed for contemporary functions such as offices, schools, and museums. Beyond meeting safety and maintenance requirements, these buildings must also ensure comfort under service loads, a challenge for structural elements like timber floors, which often hold cultural significance and are subject to preservation constraints. This limits the feasibility of reinforcement or replacement, raising concerns about performance under modern usage scenarios. This study presents in-situ vibration measurements performed in a heritage building, with a focus on the serviceability of its timber floors. Using walking and heel-drop excitations, vertical acceleration data were recorded and processed to compute Root Mean Square (RMS) acceleration levels and damping ratios. The results were analyzed across five test setups in three rooms and compared to international and Dutch serviceability standards. Findings reveal large spatial variations in both vibration response and damping behavior, driven by underlying support conditions and floor finishes. The study highlights the critical role of localized structural characteristics and contributes to the development of practical methodologies for evaluating floor performance in historic buildings under adaptive reuse.