What is Lift Slab?
Definition of Lift Slab in Construction
Lift slab, refers to a method of construction of multi story structures, that involves the placement of several concrete slabs on the ground.
These slabs of concrete are then lifted to their designated, designed elevations. The lift slab method involves the erection of steel columns supported on concrete footings and piers. The slabs are then formed around these steel columns with bond breaker membranes placed between each of the slabs cast on the ground. The appearance of the structure appears like a multi layered birthday cake with several slabs placed, one over the other. The slabs are then lifted by hydraulic jacks. As the bottom slab of the group reaches its designated, designed elevation, it is wedged off at the columns, and dropped off from the pile of slabs. This procedure continues until all slabs are dropped off and the final slab becomes the roof slab. The advantage of this system is obvious, time, money and the expediency and ease of placing concrete slabs at grade elevation. Unfortunately this method of construction is now banned from the United States due to a catastrophe that occurred in Bridgeport Ct.
The lift slab technique was extremely popular, however a structure collapsed in Bridgeport killing 28 workers. The rescue efforts of the local municipality was highly publicized, and the end result was the banning of the lift slab technique in the United States. Although the technique was a unique system of construction and resulted in several successful, stable and long lasting structures, the lack of proper safety procedures resulted in the total loss of this construction technique.