Fire Laboratory of University Centre for Energy Efficient Buildings CTU Prague was asked to perform series of preliminary fire tests preceding the full-scale fire test LEPIR II which shall be conducted in France in late January 2018. The aim of the preliminary test was to determine the influence of mineral wool density on global characteristics of a fire barrier that is used to prevent fire spread through ETICS in Western Europe countries. In the research, the change of thermal and fire characteristics of the fire barrier were assumed as the major issue, represented by a change of temperature above fire barrier. Therefore, only temperatures inside ETICS, below and above the fire barrier, were acquired and those shall be compared.