Abstract: The method for constructing a building begins by pouring slab floors from nine inches to twelve inches less than the inside width of the finished floors of a number of buildings in a project in one phase of the project work, and, thereafter trenching and pouring footings about the floors to leave a space between the slabs and the footings in a subsequent phase of the project work. The upper elevation of the footings is set to provide the desired pitch of each building roof. Precast walls are made of standard height and length and set on the footings, the lower sections of the walls, and footings both having hooked rebars adapted to be interconnected together with the mesh reinforcing of each slab floor within the nine to twelve inch "poor strip" space provided. A pour strip or closure strip of concrete is poured over the rebars and continues the slab floor to the wall surface and downwardly to the footing.