No matter what I try, I can’t put a Weather Vane on any roof. I can place them on foundations and ceilings, but not roofs. I’m sure everyone will agree that such an object belongs on top of a roof, not on a flat surface.
I tried to put different things on my roof, hoping that they could support the Weather Vane. But the only things that can be built on top of a roof, are other roofs, stairs and ceilings. With a bit of trickery, I was able to build a pillar on the crest of two meeting roofs. Unfortunately, that pillar lost stability after 3 days.
Speaking of pillars, they do lose stability quite a lot, and quite randomly, if you don’t build them smack center on foundations or ceilings. If they’re a little off-center, they will collapse at server restart, or at a random time during the day. Is that intended or a bug?