I don't agree with the person your replying to but its clear that they aren't using "nature" to mean "things happening outside" or "things happening to non-humans". When people say "against nature" almost always they are saying that something runs contrary to the nature of man in such a way as to inhibit an ordering towards flourishing. Against nature means something not conducive to the proper ordering of the human person, so a house is not in principle "against nature" since it acts in accord with human nature and furthers human flourishing rather than frustrating our natural faculties.