A thermally insulating construction component for arranging between two load-bearing parts of a building includes an elongate insulating body and also reinforcing bars extending therethrough transversely with respect, to its longitudinal direction. Bearings project from side walls of the insulating body and absorb thrust and shear forces. The insulating body includes an upper and a lower parallelepipedal dimensionally stable box member filled with insulating material. The insulating body further includes a further dimensionality stable box member which is filled with an insulating material and which is arranged as a middle box member between the upper-box member and the lower box member. The middle box member is fixedly connected to the upper box member and the lower box member.