Filler-slab roof
Born in India (popularised by Laurie Baker).
How it works
Inert filler (clay pots, tiles, coconut shells) replaces concrete in the tension zone of a slab where it isn't structurally needed, cutting cement and weight while trapped air pockets add insulation.
Where it came from
Laurie Baker, the British-born architect who built in Kerala for half a century, popularised the filler slab through thousands of low-cost buildings and the COSTFORD organisation he guided. It is his most copied invention: a roof that saves concrete by admitting that part of every slab does no work.
How it is built
In a reinforced concrete slab, the concrete below the neutral axis mostly just hangs there as dead weight. Baker replaced that zone with cheap, light fillers laid between the reinforcement: Mangalore tiles, clay pots, coconut shells. The slab uses roughly a quarter to a third less concrete and steel, weighs less, and the air pocket in each filler insulates the roof against sun.
In a modern home
Directly buildable today; pairs the Cool and Cycle pillars (less concrete = lower embodied carbon).
What it answers
Built from
Go deeper
- Gautam Bhatia, Laurie Baker: Life, Work, Writings (1991)
- COSTFORD (Centre of Science and Technology for Rural Development) construction manuals
Source
Laurie Baker and COSTFORD (Kerala), cost-reduction manuals that popularised the filler slab.