All hail the clay-woodchip partnership. Low tech, customizable, no off-gassing, pleasant to work, and when plastering, leads to rewarding skill development over time. Varied, tunable, colorable, repairable, recyclable, low embedded energy - all good.

Of course, the clay/woodchip excels in the wall- it's the roof insulation that is the bigger energy-conserving concern and more difficult to realize with basic materials like clay and pant-fiber.

Has anyone looked into amending the clay/straw/w.h.y with a bunch of perlite and casting lightweight insulative blocks?