Pour a flat concrete roof and a surprising amount of it does no structural work at all. The lower third sits in the slab's tension zone, contributing weight but little strength.
The filler slab - an idea Laurie Baker made part of Kerala's vocabulary - replaces that redundant concrete with light, inert fillers: Mangalore tiles, terracotta pots, recycled units. Less cement, less steel, a lighter slab, smaller beams below.
The fillers do a second job once the building is in use, slowing the sun's heat into the rooms beneath. And the soffit arrives finished - a quiet terracotta grid that needs no plaster and no paint.
It is a reminder that sustainability is often not a new technology but an old discipline: use only what does the work.
We write these field notes the way we work: slowly, from the material up, and only about things we have actually done. If a method here speaks to your own ground, we would love to hear about it.
