The US produces millions of tonnes of rice waste each year. Now people are building homes with it

A notoriously stubborn agricultural waste product, rice husk is now being repurposed as a sturdy and resilient construction material.

In 2023, David Fine had a problem. He had been hired to renovate a luxury ski condo development in Park City, Utah, in the US. But the building requirements were proving challenging.

The existing condos had begun to rot under the town's famous powdery snow, which piles up for months during the long winters. The homeowner's association had spent a year searching for a material that would absorb moisture while also resisting the increasingly frequent wildfires that threaten the mountaintop locale in summer.

They considered products like extruded aluminium, which would protect the condos against fire but appear synthetic. Wooden sidings such as cedar, on the other hand, would achieve a more pleasing aesthetic, but with a weaker fire rating.

Finally, they came up with an outlandish-sounding solution: panel boards made from rice husks – a byproduct of rice farming. "Their focus was to find something that looked like wood, that was beautiful, and that was a little better fire-rated than traditional wood siding," Fine says. Rice husk panels, it turned out, "checked all those boxes". 

Previously viewed as a waste product and even pollutant, rice husks are now attracting attention for their potential as a versatile, sustainable construction material. With hundreds of new homes in the US now using rice husk panelling, and other rice husk products from porches to playgrounds available, why are some developers choosing this agricultural throwaway over classic materials?

The house that rice built

While growing on the plant, rice husks protect the grains from moisture and pests. But when the crop is harvested, they become one of the most stubborn agricultural waste products to deal with.

The world produces around 150 million tonnes (331 billion lb) of rice husk each year, much of it burned on farms or at roadsides, posing risks to both human health and the environment. In the US, which grows some nine million tonnes (20 billion lb) of rice annually, rice husk is sometimes converted into biomass energy, though even then there's not always a clear use for the ash left behind.

A pioneering solution kills two birds with one stone – repurposing this agricultural waste as a durable and sustainable building material of the future.

Alongside the use of materials made from rice husks in panelling and other construction materials, research suggests rice husk ash could provide an alternative to cement, which is responsible for 8% of global carbon emissions. 

Christopher Guimond first became curious about rice byproducts when he discovered US rice producers let the waste decompose in the ground and release polluting clouds of methane, a potent greenhouse gas. An engineering student, Guimond started to believe that rice husks would make the perfect material to use at scale in construction.

"The fascination was to take this thing that was a throwaway and leverage its properties," he says.

Guimond is now the chief executive of Modern Mill, the first US-based company that manufactures construction products out of rice husks at scale. Since it was founded in 2018, the company says it has diverted over nine million kg (20.5 million lb) of rice husks from landfill, including as the panelling for........

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