The Cobute precast slabs are structurally more efficient and considerably lighter than solid slabs or even conventional rib and block slabs
— Pr.Eng. Ugo Rivera

The elements of the Cobute precast slab system

Unlike conventional rib and block systems, the Cobute precast slab is an interlocking system that consists of three elements: precast lattice ribs, precast panels and polystyrene blocks. Only minimal shuttering is required when installing it.

Technical Details

The lattice rib comes in standard width and thickness. The rib stirrup height changes according to the slab thickness, as specified by the Engineer. The stirrups are produced with high tensile steel in a continuous bent-length, providing a superior sheer-key between the precast rib and the cast in-situ topping.

Precast ribs with stepped top steel are available, as well as edge ribs, depending on individual requirements.


Precast decking detail - perforated panel to accommodate downlighters.

The precast panels are manufactured in a standard size, light and easy to install; panels complement the structure of the rib as they interlock with precision. Cobute can accommodate special requests such as creating perforated panels for light points, down lighters or speaker boxes as well as supplying narrower panels to minimise shuttering on site.




                                     Cobute precast slab - polystyrene detail

Polystyrene blocks are used as void forming material in standard width (380mm), varying in length and thickness according to the Engineer’s specifications.

The use of Polystyrene in Cobute's decking system ensures:

  • great variation in slab thicknesses
  • reduction in the amount of concrete needed
  • the light weight of the slab and structure
  • thermal (R Value) and acoustic insulation




Fire Rating and Thermal Insulation (R Value)

The R Value of the Cobute slab ranges according to the height of the slab, from 0.45 for H220mm to 0.49 for a H250mm slab. The slab holds a Fire Certificate rating of 150 minutes for a 230 mm thick slab.

Slab Size & Thickness

Cobute manufactures R.C. precast slabs in thicknesses varying from 150 to 350 mm, in increments of 25 mm for intermediate thickness. When designing different slab heights,  only the height of the lattice rib and the thickness and length of the polystyrene blocks will changewithout increasing the total amount of concrete needed. Should you be interested in designing the Cobute slab, please request the loading charts for residential and commercial loads. 

Why is the Cobute decking unique?

Cobute precast beam, decking and stair integration

  • It's the lightest slab (the dead load of the decking system is roughly 97 kg/m²)
  • It's a flexible system that suits a wide range of structures
  • It guarantees thermal resistance, reducing the energy consumption of the structure.
  • It holds a fire rating certificate
  • It reduces the amount of resource needed (concrete, steel, timber) with even greater structural results
  • Only minimal shuttering is required.
  • When the Cobute precast elements are used in combination, the project can be cast in one pour, minimising risks of cold joints and cracking

Precast beam-in-slab shows the integration of the Cobute precast elements working together

Typical Section of Cobute slab -Click to enlarge

While the system can be designed by any Professional Engineer, Cobute can supply Engineer calculations, layout drawings, completion certificates as well as NHBRC documents through a strong network of Consulting Engineers.




Visit our tooltips page or contact us to request our slab brochure.