According to a recent New York Times article, the legalization of cannabis in many areas is leading to increased consideration of hemp as a building material. Hemp has been used in structures going back to ancient times, and now there are homes being built with Hempcrete— a mixture of the woody fibers of the hemp plant with lime that produces a natural, lightweight concrete.
Hempcrete is used primarily as an insulating material and cannot substitute for concrete in a foundation. Because it's not rigid, it's more resistant to earthquakes than regular concrete. Other advantages: it's non-toxic and termite, mold and mildew resistant. There have been numerous structures built using Hempcrete, but the problem is that it has not yet been certified as approved by building codes.
The industry is growing with pioneers taking the leap ahead of the process—just like those who opened dispensaries before cannabis was legalized in some states. The movement is definitely spreading, with a Washington company retrofitting homes with it and Left Hand Hemp in Denver completing a permitted structure in Colorado. There are other projects and more information to be found online by searching Hempcrete.
Hempcrete uses industrial hemp, but there's also the potential of recycling cannabis waste from larger outdoor grow operations. There are currently waste recycling programs that use the woody fibers for making treeless paper and it's likely it could also be used for building materials.