Natural building materials are in recent years used still more often in civil engineering. One of these materials is also the straw. By its crushing and cutting into small pieces it is formed so-called crushed straw. The properties of this material, which are important for civil engineering, were not published yet unlike the properties of the straw in bales. In the Czech Republic there exist a many objects built from straw bales. In this paper there are described partial results of research which is implemented on Faculty of Civil Engineering, VSB – Technical University of Ostrava since 2013. The aim of this research it is to set fire resistance, thermal – technical properties and acoustical characteristics of crushed straw. There are described results of fire tests – flammability test and tests of single burning object (SBI). Subsequently there are referred results of thermal conductivity measurements, which were provided for different bulk densities of crushed straw.