Abstract: A building system including supports vertically disposed in an underlying surface in spaced apart relation, and support headers removably disposed on an exposed end of each of the supports. Each support header includes a mounting hub that removably engages the exposed end of the support. A span element is provided and extends between adjacent supports, each span element including a lock element that matingly engages a corresponding engagement element at the supports to removably secure the span element in position. A reinforcement panel formed of a stiff, open grid configuration is suspended from the span element along with an application panel. The application panel includes apertures defined therein to define an open mesh, and a quantity of unhardened concrete is applied to the application panel to substantially cover the application panel, the reinforcement panel and the supports, thereby defining a wall upon hardening.