An insulation material based on polymeric plastic is specified, to which glass particles that consist of types of glass with different softening points are added for stabilization in case of fire. To provide protection in a very broad temperature range, at least three types of glass with different softening points are used as the glass particles, namely, a first type of glass with a softening point below about 470.degree. C., a second type of glass with a softening point above about 470.degree. C. and below about 620.degree. C., and a third type of glass with a softening point above about 760.degree. C.