The invention relates to a method for producing sandwich construction elements for substantially load-bearing and self-supporting building parts. In one embodiment of the invention, a method is provided including a) producing at least one layer of a mechanically bonded fiber nonwoven which is impregnated with a binder based on at least one heat-curable resin system b) curing the heat-curable resin system in order to produce at least one hardened layer of the fiber nonwoven, and fixed thermally, c) bringing a heat-foamable or heat-foamed phenol resin into contact with that surface of at least one hardened layer of the fiber nonwoven which has been modified according to step b), d) possibly annealing the composite produced in a) to c), and e) curing the further binder based on at least one heat-curable resin system.