Hollow-core slabs are prefabricated slabs with holes – channels, along the cross-section (so-called. Żerań plates). The holes reduce the weight of the plate . The thickness of the plates is 24 Cm, hole diameter – 19,4 cm and the width is adapted to modular dimensions 90,120 i 150 Cm. The boards rest on the walls or on the beams and their joints (so-called locks) filled with cement mortar. The maximum span of the slab is 6,0 m.

In hollow-core slabs, ordinary reinforcement can be replaced with prestressed steel wire ropes, which allows to increase the span of the ceiling to the span from 6,0 into 18,0 m

Varieties of prestressed multi-channel plates (Sp):
o plates with a height 200 mm and lengths to 9,0 m
o plates with a height 265 mm and lengths to 13,2 m
o plates with a height 320 mm and lengths to 17,4 m
o plates with a height 300 mm and lengths to 18,0 m.

The minimum support depth of the panels Sp with a length exceeding 9,6 m is 80 Cm.

Filigran composite ceilings are slab ceilings made of prefabricated reinforced concrete slabs with a thickness of 5 into 7 cm flooded with a layer of concrete, the thickness of which depends on the span and the expected load on the floor. The precast concrete slab of B-25 class contains concreted ceiling reinforcement and steel truss beams constituting additional stiffening. The joints of prefabricated slabs are reinforced at the construction site with meshes to avoid this phenomenon “keying” ceiling. The prefabricated slab is the lost formwork for the poured concrete layer, which may or may not be armed. Filigran boards have a standard span up to 9,5 m and any shapes (triangular, trapezoidal, semicircular – as you ordered). Economically justifiable, that the span of the ceiling on the Filigran panels does not exceed 7,5 m. Filigree ceilings are calculated in the same way as monolithic ones, reinforced concrete slab ceilings. The minimum thickness of the entire floor is 14 Cm.