What is jackblock construction?
Jackblock construction is a building technique in which a building is put up from the top down by jacking completed floors upward. First the top storey (the roof) is built at ground level. It is then jacked up by one storey height, after which the next storey is formed beneath it. In this way the building grows from below, while work is always carried out at ground level.
Method
The method proceeds in repeating steps:
- Building at ground level — each new floor slab and the walls are made at working height, which is safe and efficient.
- Jacking up — hydraulic jacks on temporary or permanent supports push the part above upward.
- Repeating — the next level is built beneath the raised part; this repeats until all the storeys are in place.
Advantages and application
Because almost all the work is done at ground level, fewer scaffolds and high workplaces are needed, which benefits safety and working conditions. The method has been used for concrete residential towers and silos, among others. Drawbacks are the heavy, precise jacking technique and the careful coordination required; the loads and the jacking must be properly calculated. Jackblock construction is related to other “lift” techniques such as lift-slab, in which floors are cast and hoisted up.
Related terms
- Building method
- Concrete frame
- Industrialised building
- Formwork
- Lifting beam
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