Roofing with Filler slab

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Example of terra cotta pot as filler


Filler slabs are one cost - effective roofing system which is based on the concrete portions and instead placing filler material there.


The filler slab is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and the lower part of the slab experience tensile forces. Concrete is very good in withstanding compressive forces and steel bears the load due to tensile forces. Thus the lower tensile region of the slab does not need any concrete except for holding the steel reinforcements together. Therefore in a conventional RCC slab lot of concrete is wasted and it needs extra reinforcement due to added load of the concrete which can otherwise be replaced by low-cost and light weight filler materials, which will reduce the dead weight as well as the cost of the slab to 25% (as 40% less steel is used and 30% less concrete). The filler slabs also result in fewer loads getting transferred to the load-bearing walls and the foundations. The air gap in between the tiles makes it a good heat insulator and the ceiling looks attractive as well.


  • Bricks
  • Tiles
  • Cellular
  • Concrete
  • Blocks
  • Pots
  • Waste bottles

Details and experiences

The mechanism The filler slab is a mechanism to replace the concrete in the tension zone. The filler material, thus, is not a structural part of the slab. By reducing the quantity and weight of material, the roof become less expensive, yet retains the strength of the conventional slab.

Thermal insulation The air pocket formed by the contours of the tiles makes an excellent thermal insulation layer. The design integrity of a filler slab involves careful planning taking into account the negative zones and reinforcement areas.

Thus the filler slab as the roof has the following advantages: • Consumes less concrete and steel due to reduced weight of slab by the introduction of a less heavy, low cost filler material like two layers of burnt clay tiles. Slab thickness minimum 112.5 mm. • Enhances thermal comfort inside the building due to heat-resistant qualities of filler materials and the gap between two burnt clay tiles. • Makes saving on cost of this slab compared to the traditional slab by about 23%. • Reduces use of concrete and saves cement and steel by about 40%.

Filler slab with terra cotta pots as fillers

Filler slab roof construction where inverted hemispheres of terra cotta pots are pre cast and made to rest over reinforced concrete beams before the concreting process. Here indigenous building materials are incorporated, techniques that absorb and relate to other forms of design and materials regardless of the field they originally belong to, and locally appropriate aesthetics have been applied to bring these forms in the mainstream, rather than patronizing them as alternative architecture.


Example filler slab

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