Comparison of standard software predictions of the sound insulation in CLT and concrete buildings with field measurements

Within the research projects AkuLite, Aku20 and the current AkuTimber at LTU, more than 30 newly built wooden buildings have been examined since 2010 by means of detailed field measurements of sound insulations and vibration transmissions. The field results were used to look into a question of practical interest: - When acoustic consultants apply commonly used calculation softwares and their own experience, how close to the real performance is reasonable to assume they will get, on the average? To find out, a selection of building cases examined in the research projects have been studied, amended with a few external measurement results. The first estimates of DnT and LnT were made from the drawings only. The second estimates were supported by the measurement results and vibration transmission measurements to refine the models of the junctions. 30 field measurements of DnT and LnT in buildings with CLT floors as well as 17 measurements in concrete buildings have been compared to calculations made according to EN ISO 12354. The results are presented as average (systematic) deviations and standard deviations, combined to provisional safety margins of 5-8 dB for LnT,w in CLT and 2- 3 dB for concrete buildings respectively.