Modern Mill Now Offers Its Rice Hull–Based ACRE Siding and Trim in Factory-Finished Options – GreenBuildingAdvisor

By Justin R. Wolf | January 20, 2026

The so-called waste-to-value economy is a burgeoning field that is producing some truly exciting products. Consider the use of biochar made from processed sewage sludge as an additive in concrete mixes or harnessing the recycling power of mycelium to digest organic matter in discarded carpeting, yielding a fibrous and chemically inert feedstock for other products. These are just two examples of biomaterials at play. Of course, neither has achieved anything resembling scalability, and the latter is barely out of the lab. Still, many technological innovations are viable, especially when you isolate case studies to the sub-category of agricultural byproducts.

Some notable examples include the upcycling of hemp, straw, wheat, and bagasse (from sugarcane) for various insulations and composite building materials. Another concerns the use of discarded rice hulls, which are proving quite versatile across a range of product categories, from supplementary cementitious materials (SCMs) for concrete to siding and trim board for homes. Back in 2023, GBA contributor Fernando Pagés Ruiz wrote about a new product called ACRE, from Modern Mill, a wood alternative comprising 50% rice hulls and another 50% made from a proprietary mix of PVC-based resin compound and other stabilizers.

In addition to ACRE’s workability and lack of static charge, Ruiz notes how “the material will not melt even when cut with a dull blade, it has no toxic gasses or friable minerals, [and] it can take conventional wood stains.” These attributes have made ACRE a highly in-demand product. It has also been marketed as the “only stainable” composite in its product category. But as more manufacturers are making the shift to less toxic, low-VOC, and water-based paints and stains, this has resulted in some logistical challenges when it comes to on-site staining. Modern Mill has responded with a new line of factory-finished ACRE siding and trim that comes…