The goat house now has a floor, all its walls, and half a roof! It has also been jacked up and set back down on (scavenged, naturally) concrete blocks to prevent the wood beams from rotting in the Oregon moisture. The top 1/2 of 3 walls will be left open for ventilation and light, and shuttered during any cold winter storms.
Investment so far: about $50 for roof beams, screws, tar paper (partial rolls from a local construction materials reclamation facility called Bring Recycling.), and a roof vent (also from Bring).