I'll bring into the thread, connected right away with the question of whether Stommel also offers shell houses :)
Answer: yes. They offer several stages of completion. Classic is: shell house (only the walls, windows, doors, and roof are in place), shell construction (roof covered, insulated, drainage, ...), then the technical package electrical/plumbing/heating, then floor coverings, painting work, doors, and stairs.
I only read the first page of the thread (I stopped at the OP's wall construction, it's not my thing). Why Stommel?