All too often the concrete in a concrete house gives way at the roof line to conventional stick construction. Not so with a system recently developed in Florida using expanded polystyrene foam forms, shotcrete walls, and pumped concrete on the roof.
Eight-foot-tall expanded polystyrene wall panels 9 1/2 inches thick are set on a conventional floor slab with pressure treated wood 2x4s between them at 4-foot centers. On the outside of the house, notched panel edges serve as forms for columns shotcreted integrally with exterior walls. The wood members accurately position and support reinforcing bars in the columns. A 2-inch concrete skin is shotcreted on all vertical surfaces, and the column form recesses are filled at the same time. The 2-inch thickness of roof concrete is pumped into place on the gentle slope. A low-slump 3000-psi mix is used throughout.