Modern Mill
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.
A pioneering solution kills two birds with one stone – repurposing this agricultural waste as a durable and sustainable building material of the future.
Modern Mill
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 Fine's ski condos.
It is often easier to adopt a new floor tile material than it is to adopt a new material for a beam – Sabbie Miller
Rice husks protect the precious grains from wind and rain, and their high silica content allows them to resist moisture and decay, meaning they naturally boast the same properties as many traditional construction materials. "The whole point of the rice husk is to protect the rice while it grows," Guimond says. "What is it protecting it from? Moisture, pests, rot, those types of things."
In addition to protecting against moisture, the high silica content means rice husks are surprisingly resilient to fire, according to Fine. Modern Mill's product is designated as Wildland Urban Interface (WUI) compliant, meaning it has passed California's fire safety testing.
The benefits of rice husk
Timber has long been considered a sustainable building material. It is abundant in continental climates and has comparatively low carbon emissions compared to materials like concrete and steel.
Modern Mill
A recent study found that using the fibrous residues from crops like rice, wheat and maize for buildings, rather than burning them, could produce a significant carbon sink, since the carbon caught in these residues would be locked away for decades.
Sabbie Miller, an expert in sustainable building materials and professor in civil and environmental engineering at the University of California, Davis, notes however that whether or not a particular building material will be low-carbon can be very nuanced and requires a detailed life cycle assessment.
The house, designed to rebuild a previous structure, features large south-facing windows and an open kitchen that brings sunlight and air but also seasonal heat and echoes. "We had to add another way to insulate more and guarantee acoustic comfort," says Valentina Savioli, a communications officer at Ricehouse. Using rice as insulation was an easy decision "just because of how much volume and biomass [it] has", she adds.
However, more widespread adoption might prove tricky since Italian contractors are generally sceptical of less common building materials, says Savioli.
There can be similar concerns in the US, as well as barriers like cost, says Miller.
"There can be hesitancy to use materials if, for example, an engineer could compromise their license or ability to get hired if there is a material failure," she says.
Modern Mill
However, adoption of non-load bearing rice husk products (the case for Modern Mill's panels) will likely face fewer challenges than using them in load bearing materials, she adds. "It is often easier to adopt a new floor tile material than it is to adopt a new material for a beam."
Concrete alternative
Some US states, however, do already approve alternative structural materials such as earth blocks (made from dirt mixed with water and chemical stabilisers) or hemp.
A 2025 study proposed combining rice husk ash, wood ash and rice straw to make a low-cost, carbon-negative material that could eliminate the need for cement.
In Africa, for example, new construction usually uses concrete and suffers from poor quality. "It’s like the worst of both worlds," says Ariana Karamallis, director of global engagement at housing non-profit Build Change, based in Colorado. When using innovative materials like rice husk, she adds, it's crucial to find a "sweet spot" between affordability, scalability and relating to the community – and to avoid testing novel techniques on the most vulnerable.
Rice husk may have the most long-term potential in rice-producing areas of the Global South, but it is already being used in buildings in the US.
Since the Park City condo project was completed, Fine has used rice husk panels in five additional projects, with several more in the pipeline. While it costs slightly more to install compared to cedar, the long-term maintenance costs are lower due to its resistance to moisture, sun and fire, he says. He believes rice husk products are on the cusp of becoming competitive and will likely beat cedar in price once more people learn how to install them.
"I'm always looking for ways to put a product out that will last a long time, longer than hopefully I'm alive," he says. Rice husk products, he says, might prove to be just such a material.