Abstract: A building system for wall construction utilizes a prefabricated panel having two layers of foamed insulating sheets sandwiched around a layer of concrete or other cementitious material. Channels are cut into an interior face of one of the panels. The channels receive cement, which provides a reinforcing structure when hardened. Steel vertical channel studs encase the sandwiched layers on two sides of the panel. The vertical channel studs have a vertical surface which is fastened to a similar, opposing vertical channel stud of an adjoining panel to effectively create a vertical I-beam support when the panels are assembled together. The panels of the invention can be readily transported to a worksite, assembled, and finished on-site with a stress-skin to yield a wall which is extremely rigid, insulative, and resistant to forces such as fire, water, termites, and impact.