Abstract: A precast panel for a building comprises a pair of molded concrete inner and outer panel elements with a steel wire mesh embedded throughout each panel element. A series of laterally spaced continuous steel rod trusses are interposed between and extend at right angles to the panel elements with end portions of the trusses embedded into the panel elements. An insulating layer overlies and is bonded to the interior side of the outer panel element occupying part of the space between the panel elements, the remainder of the space providing an air barrier zone. Pairs of aligned panels and right angularly related corner panels are interconnected by a concrete column poured in situ between the adjacent panels.