Sound insulation of access floors on CLT

Access floors are raised floor systems widely used in commercial or office buildings as they allow easy inspection, substitution, and interventions on the building systems and wiring that are housed in the cavity. The acoustic performance of access floors resting on concrete slabs has been long investigated but if such systems rest on lightweight floors, the estimates of impact sound insulation improvements cannot be used without relevant loss of accuracy. To gain understanding of such behavior, an experimental campaign has been carried out at the Building Envelope Lab of the Free University of Bozen-Bolzano on 16 access floors mounted on a 200 mm CLT slab. Three different top panels (calcium sulphate, encapsulated calcium sulphate and encapsulated chipboard panels), two different pedestals (standard and with resilient mount), and three flooring solutions (bare, carpet tiles, acoustic carpet tiles) were tested. Impact sound insulation measurements were carried out using both the tapping machine and the rubber ball as source. The results show that the impact sound insulation performance of CLT floors is not strongly affected by the type of panel used and that significant differences emerge when access floor performance is tested using the tapping machine or the rubber ball.