Sections of rib-and-slab ceilings: a) costal, b) box, c) prefabricated sand-ribbed; 1 - rib, 2 - top plate, 3 - bottom plate, 4 - wooden box or aerated concrete or polystyrene blocks, 5 - suspended ceiling (suprema and plaster), 6 – prefabricated ribbed plate length 590 cm, 7 - upper plate with dimensions 34 x 82,5 cm.
Reinforced concrete ceilings. These ceilings belong to the group of rib-and-slab ceilings, in which the spacing of the ribs (belek) does not exceed 100 cm.
Ribbed reinforced concrete ceiling. Presented in fig. 6.59and the ceiling is used for higher loads and there, where a smooth underside is not required, e.g.. in storage rooms, parking lots, etc.. In residential buildings and indoors, where people stay, ceilings with a smooth surface on the bottom are made (Lynx. b).
Both due to the favorable insulating qualities, and the lower weight of the structure, ceilings with internal air space were widely used, the so-called. box ceilings. The boxes or molds are placed on the previously made lower ceiling tile, and then stacks up, reinforcement bars and concretes the whole thing. Recently, blocks of plastic or other materials can be used instead of boxes. The thickness of the bottom plate is 3 cm, upper 5 cm.
Due to the difficulty of execution and the high cost, box ceilings are used less and less.
Slab-ribbed ceiling. Figure c shows a prefabricated floor with a smooth surface on the underside, which can be made of ribbed plates with the ribs upside down. Reinforced concrete tiles are placed under the floor on the ribs. The shown SPS ceiling has rib spacing 60 i 90 cm and height 30 cm.