Rice hulls have a number of construction uses including as insulation, concrete filler, and a component in engineered wood products. Products made with hulls are available in some hardware and home supply stores, and it is also possible to order them directly from manufacturers. For the agriculture industry, finding uses for waste products is advantageous as it makes their practices more environmentally friendly and provides a market for byproducts that previously cost money to discard.
As insulation, they have a number of useful properties. They resist mold and mildew and have very high insulation values. Some historic structures show evidence that earlier societies reused their rice hulls for this purpose, and the trend toward recycling in the 2000s is a return to older practices. People can use hulls as blow-in insulation just like cellulose, recycled paper, and similar products. It is also possible to pack rice hulls in bags and use them in bagwall construction, where people pack bags with insulating material and stack them between supporting materials before plastering with adobe or similar products to create a wall. This green building technique can be used in a variety of climates.
In concrete filler, people can use burned rice hulls as part of the aggregate material in the concrete. Burning is a common practice for eliminating agricultural waste, and people usually discard the ashes. In concrete, they can act as a filler and binder to hold concrete together, replacing other materials. While burning is less environmentally sustainable than using raw rice hulls, in situations where companies are likely to burn hulls anyway, reusing them in concrete provides a better method for disposal than the landfill.
Engineered wood products like composite decking and planking can use rice hulls. These materials provide people with environmentally friendly alternatives to wood and they tend to be more durable and resistant to chemicals, harsh weather, and other sources of damage. Companies can dye or stamp engineered wood in a variety of ways to create patterns and make it more visually interesting. It is often possible to order custom versions, although they will be slightly more costly.
Companies using rice hulls in their products will usually disclose their percentage by volume and should discuss other components as well. Products containing recycled agricultural products are not always more environmentally friendly, depending on the other components of the product. It is a good idea to research thoroughly before making any purchases. Resources can include green contractors, informational books and pamphlets, and organizations with an interest in environmentally friendly building practices.