Abstract: An insulating building block made up of an insulating core and two concrete walls is configured such that the core comprises locking protrusions to interlock with preformed cavities in the concrete walls.

Abstract: An insulating building block made up of an insulating core and two concrete walls, each cast over one side of the core. The latter comprises a body having opposed parallel flat outer faces, bound by parallel longitudinal edges and parallel side edges, and having a transverse plane normal to the outer faces centrally between the longitudinal edges. Locking protrusions are formed integrally with the body and project from the outer faces. Each protrusion extends from either side of the transverse plane toward the longitudinal edges and terminates short of the longitudinal edges. The protrusions have outer surfaces and lateral edges tapering inwardly between the outer surfaces and the body outer faces. The protrusion side edges further make angles with the transverse plane suitable to facilitate demolding of the core when the core is molded in two half molds having a closure plane co-planar with the transverse plane, aforesaid.