Abstract: The invention relates to a sound proof composite system for space limiting surfaces comprising at least one coating layer (V) and one insulating layer (D)) made of at least three additional layers. By using modified polyolefins having at least a required higher percentage of comonomers in order to obtain said properties, more precisely in the form of m-PE/m-PP (VLDPE/VLDPP) or a soft PVC sheet (I) as a core for the insulating layer (D) in combination with at least two external single or multi-layered sheets (A) containing a barrier substance (A1), it is possible to obtain densities of the insulation layer (D)) of less than 1600 kg/m3 while ensuring good sound-proof qualities.