Lime, stone, and the slow architecture of the South

There is a wall in a house in Chettinad that I have been thinking about for three years.

It is built from Athangudi tile and lime plaster, the lime mixed with egg white in the traditional method, polished to a surface so smooth it looks almost wet. The wall is perhaps a hundred and forty years old. It is, without question, one of the most beautiful surfaces I have ever seen in a building — and the beauty is entirely a function of time. No new wall looks like that. It takes decades of humidity and expansion and contraction and the slow chemical processes of lime carbonation to produce what that wall has become.

The South of India has a material tradition that is, by any serious assessment, among the most sophisticated in the world. Lime. Stone — granite, laterite, Kadappa. Teak. Clay tile. These materials were selected over centuries not by architects with degrees but by builders who watched what lasted and what did not, what stayed cool in summer and what did not, what could be repaired by the people who lived in the house and what required a specialist.

What our grandparents understood, and what we have largely forgotten, is that the best building materials are alive in some sense. Lime is made from stone that was once marine organism — it is, in effect, fossilised sea. It continues to react with its environment for centuries after it is applied. It breathes. It adjusts to humidity. When it cracks, as all lime eventually does, the cracks are fine and can be sealed with more lime, by anyone, without tools.

Concrete does not do any of these things. Concrete is an extraordinary structural material that has been asked to do things it was never designed to do — to finish surfaces, to sit exposed to weather, to age gracefully. It does none of these things well. It carbonates from the outside in, causing the steel inside it to rust and expand and eventually crack the concrete. It traps moisture. It cannot be repaired by the people who live with it.

We use lime on every project we build. We use Kadappa stone for flooring where we can. We use Mangalore tile on roofs. Not because these materials are fashionable — they were, in fact, deeply unfashionable for most of the period during which we trained as architects, dismissed as vernacular or backward — but because they work. They have been tested by the climate we build in, across a span of time that no modern material can claim.

Returning to these materials is not nostalgia. It is attention. Our grandparents used what the land provided and what time had validated. We would do well to pay the same kind of attention.