Pretty cool. Can't say I've ever ran across a house or building like the OP posted.

Looks like rough cut lumber or as was done in the old days, a true 2x4. Wonder if it's something like chestnut or locust? Can't imagine most other woods would hold up untreated. Surely there is others, but those 2 hold up to the elements and chestnut would've been around yet in all likely hood when that old place was constructed.

One is alone in a land so vast, there is only the mountains, the wind, and the eyes of God.