Anything that is atached to the ground and can not be moved around is a building.
Sections of pre-fab plywooden leaning against something, haybales arranged in a U, chicken hoobs, all those things are,,,,, not exactly a building, lol.
I am getting the feeling in america you don't needed to consider what is a boilding. Maby you pay a lot less taxes for owning buildings (compared to us) and that is why my unwillingness to own more buildings than abselutly nessesary is alien to you. It is simply a choice betwene land or buildings, at least until I win the Lotto, and I would rather buy an extra hectare (2,4 acres) of land or forest than use that money on taxes for a building that is not 100% needed.
Thanks for the good input so far, allso there are a lot to harvest from around this forum and sister sites. So far I am leaning towards chickens or geese as the first animals, but I have not been scared of by those pigs or goats. Probably one of the two will fallow if I can manage it.