A french company has patented a system for multi-story construction that uses a steel frame for the building to lift floor slabs into position. The system relies on precisely adjusted steelwork. The system's advantage lies in the fact that less than 5 tons of lifting tackle are needed to raise the cross frames, floor slabs and wall cladding. As soon as the foundations are ready, a series of steel columns, equal in height to the stack of floor slabs to be cast plus 1 foot, are attached to the main column bases of the building. These "pilot columns" set out the plan of the construction accurately. Next the floor slabs are cast in the space between the pilot columns. Four lugs, made as brackets of channel steel, are located at each corner of a slab; they project some 3 to 4 inches and are each capable of supporting 4 tons. Two types of slabs are used. The first, an eggcrate type 8 and three-fourths an inch thick, has longitudinal and transverse ribs at 18 inch centers. The second type, 6 inches thick, is solid and is used when under floor heating elements are to be cast in. Steel content is 2 and two-thirds pounds per square foot giving a total weight of 77 pounds per square foot. When the side forms have been stripped, the stacks of slabs are used as a platform for the erection of the main steel frame. Each transverse section across the building is assembled with all its base ends connected to the temporary hinges on the top of the pilot columns. When assembly is complete, the whole transverse frame is then pivoted until it is vertical. Once all the framework members are in position, the temporary hinges are removed and final joints are made between the pilot columns and the main columns. Four wire ropes are then attached to the four lugs in each slab and lifting begins. With all the floor slabs of a story in position, casting of the reinforced connecting strips can begin. The facade of the building is finally clad with precast panels.