Homeowners returning to their burned-out homes in southern California are facing the painful consequences of the US construction industry’s reliance on cheap plastics and petroleum-based building materials: Not only are these materials easily combusted in a wildfire, but they leave behind a toxic soup that has polluted waterways and poisoned air quality.

Hemp building materials were officially approved in the model US residential building code at a Louisville, KY public hearing overseen by the International Code Council (ICC) last week.