I picked up a second hand book in Oregon 5 years ago: Mike Oehler’s ‘$50 and up underground house book’. After studying and working with many natural building systems, and ultimately, using simply the earth for wall & roof is the most direct & simplest way to build ecological. This is a prefabricated and modular adaptation using standard Plywood & OSB. I recently gave a presentation at the American & Canadian Plywood Associations. There are two issues when it comes to using plywood & osb as a base material: one is the formaldehyde off-gassing from the glues, although deemed safe, it is still something I have my questions about. The second issue is when you use plywood to make beams: The ply layers grains run perpendicular from each other, this gives plywood its strength when a force is placed on the surface. In the case of a build up beam: when you place a vertical force on the edge, although glued together, halve of the ply layers don’t add to the strength for structural calculations since halve of the grains go in the same direction as the force. Adaptation would have to be to add lumber below the beams or use Laminated Veneer Lumber, called LVL’s.
Here is the full presentation: