As a side note, The use of clay on the exterior of the Bohlenwand seems like a very good idea to me, provided it is sealed by the plaster. This is because a silt-clay loam is highly hygroscopic (unlike pure clay) but does not retain high levels of moisture (unlike pure silt). This means it draws water more readily than the wood will, so it effectively keep the wood dry under normal conditions, and it at the same time will readily diffuse the water into the atmosphere after the moisture event has passed.
Would the clay plaster have a lime plaster on top of it? Or at least limewash?
It seems that clay exposed to weather wouldn't last.
I do like the way moisture would be managed. I wonder if adding foam in the cavity would cause problems with that...
