Core-insulated double walls are a widely used product that can be manufactured economically and in high quality. The trend is increasingly towards construction with as few thermal bridges as possible and the optimisation of the insulation values of the walls. A large number of possible thermal bridges can be eliminated with shear connectors made of glass fibre reinforced plastic (GRP), which is barely thermally conductive. Spacers are frequently used in addition in order to ensure dimensional accuracy with regard to wall thicknesses. As a consequence it can also be spacers made of GRP with which further thermal bridges can be eliminated.