Abstract
Lightweight building systems in general suffer from limited sound insulation, especially at low frequencies. Furthermore, theoretical models have severe limitations regarding prediction of the impact sound insulation and the design is to a high extent based upon experience and measurements. Recommendations in Norway includes the frequency range down to 50 Hz, which means to include the spectrum adaptation term CI,50-2500 and C50-5000. One possible solution to improve the properties at low frequencies is to add mass and increase the stiffness of the construction. We refer to lightweight building systems combining wood and cement-based materials as hybrid constructions. The paper will present analysis of relevant measurement results of hybrid wood joist floor constructions from laboratory and field objects. The paper will discuss possible improvements of such floor constructions. From the "Silent Timber Build project", some relevant laboratory measurement data exist. Due to the impact sound insulation focus, some apartments with hybrid joist floors have been built and data collected. This paper is part of a project at SINTEF Building and Infrastructure aiming to develop robust solutions also involving HVAC components inside the partition structure. Further progress in this project will include new laboratory measurements and fire test.