Abstract: A prefabricated consumable assembly for forming a concrete wall structure includes a pair of spaced apart side plates interconnected on their ends by transverse tie members. A single or a pair of insulating panels is positioned within the side plates and structure is associated with each tie member which defines grooves for receiving and holding the side edges of the insulating panel or panels. The groove defining structure may be formed by a detachable clip mounted on the tie members or entirely or in part integral with the tie members. Mechanism is provided for interlocking assembled ones of the prefabricated assemblies to form a wall structure including an inside corner. The side plates may be arranged for bending to form corners.