In recent years the concrete industry has made exciting and dramatic progress in developing the capability to make houses in parts and fit them together. Today some precast manufacturers even furnish complete buildings packages that include land, design, construction, landscaping, financing and property management. As a result the precast concrete industry has become a mature and important force in the building field. A traditional building method that the ready mix industry calls its own is one that uses tilt-up walls for one-story structures, usually industrial or commercial buildings. A new building technique that the ready mix industry might also call its own is the one described below for multi-family residential structures. This system is a site precast concrete technique that has been called both site-crete and site-cast concrete. The panels are first constructed in a flat position in slacks, one panel on top of another to permit assembly line constructing methods to be used. The casting crews move form stack to stack at ground level, following procedures similar to those used in mass production of large items like aircraft and ships. This system permits an even flow of the different craftsman and materials throughout the project and minimizes dimensional errors. Stacking also minimizes the amount of space needed in the casting yard. Panels are particularly applicable to the site-cast technique because their use permits architectural flexibility to the degree necessary in multiple-unit construction. With panels variations can be made in floor plans without too much difficulty. Moreover, joints can be concealed behind partition walls or under drop ceilings and carpets. The panels can be quite easily constructed in a flat position and set in place using methods similar to those for tilt-up construction.