The floor slabs, also colloquially referred to as filigree floors or half-finished slabs, are used in residential and industrial construction. They are preferrably used in combination with sandwich walling systems to create monolithic constructions and are characterised by their low weight. This enables the precast parts to be installed on construction sites, using cranes with lower load capacities.



As a result of the low weight / volume, the transport costs to the construction sites are correspondingly lower than for traditional precast concrete slabs. The floor slabs normally consist of a 40 - 60 mm thick concrete board, longitudinal and lateral reinforcement and trusses in a lateral direction. The trusses consist of welded concrete steel, the visible top member bars, two concrete cast bottom chord members and the diagonals between the top and lower members. The top surface of the slab is left in a untreated state which, in conjunction with the diagonal chairs, creates perfect bonding between the precast parts and in-situ concrete.

Elements such as electric sockets, services, openings, etc. can be pre-formed and installed in the floor slabs. Following positioning on site, extra reinforcing bars are inserted through the support chairs.Supplementary reinforcement is required where the slabs butt against each other. This lateral reinforcement must be fixed with steel wire, so that it cannot be displaced during on site concreting operations. Furthermore, it must not lie directly on the finished surface, an adequate concrete cover must be maintained according to local requirements and the planned design life-span.

Empty conduits for electrical services can also be laid before concreting works commence. The floor slabs must be supported during the concrete curing process. This is classed as lost formwork and the underside of the floor slab is characterised by its high surface quality = the underside of the slab is designed for the direct applications of wallpaper and paint. Plasterwork is not required, the joints between the individual slabs (up to 3 m wide) must be filled.