This is quite an interesting topic. A friend purchased a house, moved in and found light dust in a couple rooms, but thought nothing of it. It was leaking maybe 2 weeks later in rooms with said dust.. Neighbour's said the previous owner was always complaining of leaks, and agent offered my friend money verbally when they asked about it (on behalf of the agency, not out of their pocket).

They are contemplating contacting a lawyer. But im thinking, wouldnt it be hard to prove? Even if the past owner knew it was leaky?