Sound insulation of multi-storey houses: A summary of Finnish impact sound insulation results

Evidently a wooden house can be built so that modern requirements for both airborne and impact sound insulation are met with sufficient margins. However, low-frequency impact sounds produced by walking may be either audible to the building occupants or felt by them as non-audible vibrations. It is clear is that the present rating methods and also perhaps the tapping machine are inadequate where wooden floors are concerned, because the results may be subjectively confusing. The present situation, where internationally there are several rating systems leading to different numerical results for the same building element, needs to be addressed. Existing methods should be developed into a single international method covering all types of floors. The question of how to rate low-frequency (32 -100 Hz) footfall noises, which may not be simulated adequately by a tapping machine and rated with present methods, must be considered as a special problem separate from the general rating system. It is generally recommended to add to the mass and stiffness of the wooden floor (for example, by adding a concrete layer) to improve its overall vibration and impact sound insulation behaviour. Such floors are believed to better satisfy the requirements of building occupants.