Acoustic performance of cross-laminated timber system (CLT): in situ measurements of airborne and impact sound insulation for different configurations

Standardized methods to design and predict the acoustic performance of buildings from the performances of elements EN 12354-1 and -2, are no longer valid, if refereed to prefabricated construction systems like CLT. Consequently, the in-situ evaluation of airborne and impact sound insulation plays a key role for the investigation and characterization of CLT technology. Moreover, in prefabricated construction systems, the joints between the various structural elements (floor, walls etc.), must be carefully designed: flaking transmissions can become the weak point of such structures. As a result, the in-situ evaluation of airborne and impact sound insulation is the most appropriate way to check the real acoustic behaviour of specific constructive systems. In this paper, a measurement campaign on a multi-family dwellings in Italy (made using the CLT technology), is reported. The measurements mainly focus on impact sound insulation aspects; six different floor solutions has been measured. Both dry and traditional cement-based screed has been observed. The improvement due to the filling of the ceiling cavity, made of mineral wool absorbing material has been also assessed. The comparison between the different solutions shows that dry screed, in combination with resilient material like mineral wool, together with suspended ceiling with absorbing material placed in the cavity, provides the best performance. In-situ measurements on a CLT partition wall has also been performed. The result shows an high airborne sound insulation level. A comparison between a traditional separating wall and a CLT one has been reported.