Chalmers University of Technology in Gothenburg, Sweden, aims for a major contribution to research and development in the field of microelectronics. One step is taken by creating a new centre for R&D. The building holds in total 18000 m<sup>2 </sup> of research facilities, including a cleanroom of 1000 m<sup>2</sup>. The cleanroom is incorporated together with media supply and air conditioning as a separate unit within the main building. Due to extreme requirements on low vibration levels, the structures are completely separated. A second facility with similar requirements on low vibration levels is created inside an old building for physics research. The issue of vibration reduction and isolation from the surroundings is the subject for this paper. Requirements on maximum vibration levels are described as well as the vibration sources involved. Major sources are walkers and tramway vibration. The shortcomes of the original constructions and the measures taken to improve the dynamic performance of the floor structures are reviewed. Vibration reduction methodology includes damper design and installation as well as dynamic simulation using finite element calculations. Finally, the results from verifying measurements are presented.