Homeloan approval without approved building plans

I am not sure where to start but I want to ask , how possible is it that a bank will approve a sale of a house and afford one financing when there are no approved building plans and engineers reports. I have come to realise that it is a requirement by all banks. The question I have posed to them and they are not answering me. This I raised as a result of discovering that the house has no approved plans at Council, extensions were done and you would call them ******* now. Cracks have developed in the structure where new additions were done, these were covered by fresh paint when we moved in and now it is 3 years they just cracked open