₹850 hack that cools your rooftop: here's how this man brought his roof to 30°C in 44°C heat

At 4:15 in the afternoon, with temperatures outside hitting 44°C, a man named Ritesh was standing barefoot on his rooftop, and the surface under his feet was barely warm.

A video capturing the moment has spread rapidly across social media, drawing attention not just for the spectacle but for what Ritesh claims made it possible: a simple lime-based coating applied to the roof that he says brought the surface temperature down by roughly 15 degrees, to around 28-30°C, even under direct afternoon sun.

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What he used and how he did it

The materials are straightforward to source. Ritesh used 20 kg of lump lime, commonly known as chuna, which he bought for around Rs 350, along with 5 kg of Fevicol DDL binder and 500 grams of a waterproofing compound called Universal Repair Polymer, priced at approximately Rs 200.

The process, as he explained in the video, begins the night before. The lime is soaked in about 50 litres of water and left overnight. Once the mixture has cooled, the binder and waterproofing compound are stirred in and the resulting mix is applied directly to the roof surface. He recommended at least one coat, with a second if enough material remained.

For a 1,000-square-foot roof, Ritesh put the total cost at around Rs 800 to Rs 850.

"The temperature outside is 44°C, while the roof temperature is around 30°C, and it's 4:15 in the afternoon under direct sunlight," he said. "You won't need to rely as much on coolers or air conditioners. Even a fan will start giving cooler air."

What the internet made of it

The video, originally shared by X user Dinesh K Sen, drew a wide range of responses, most of them supportive and grounded in the science of reflective surfaces.

"Great jugad bhai! White reflective coating is real science — it reflects most of the sun's heat instead of absorbing it. Proper cool roof coatings or even a good lime + binder mix can drop roof surface temperature by 10-20°C and indoor temperature by 4-6°C on average (sometimes more in single-storey homes).," one user wrote.

"These days, desi innovation is no less than technology. If roof cooling is done properly, the load on air conditioners can be reduced significantly," another user wrote.

A third user wrote, "That's some seriously powerful tech, bro—got the job done for super low cost."