Lift slab construction has become a basic method of economical concrete construction, especially for office buildings, apartments, parking garages, hotels and other structures characterized by repetitive framing from floor to floor.


Basically, the method entails casting floor and roof slabs on or at ground level and jacking them up into position. Special lifting collars or shearheads are provided in the slabs at columns. Bond breaking compounds are applied between slabs to separate them. After the slabs have cured long enough to reach a prescribed strength, powerful hydraulic jacks mounted on top of the columns lift the slabs into their respective positions. The big advantage of erecting concrete buildings using lift slab construction is elimination of most formwork, an especially important factor in areas where labor costs are high. Concrete floor construction at ground level is convenient and requires no shores, scaffolds or cranes.

A new lift slab system has evolved in which concrete bearing walls are lifted simultaneously with the slabs. Concrete bearing walls are cast flat in the same stack with the slabs and attached to the slab with loops of plastic rope, forming hinges. As the slab is raised, each wall panel automatically unfolds into position. Since the walls are load-bearing, there is no need for expensive steel columns or lifting collars as used in conventional lift-slab work. The steel columns used for erection are removed and reused elsewhere.