"The question is: on the knob side of the door, do you think I should put a wood piece as that door stop, or just have cob and plaster for that, with perhaps a deadman in place for the lock/clasp to go into?" I would most definatley install a wooden stop for the door. The stop is bound to take a beating, and if you go with just the cob and plaster it will crack/crumble over time. -Chris Reinhart