Talk to both your realtor and attorney. If another buyer comes to the house with the same type of mortage, they will have the same concerns. You made an offer and contract on the house with the knowledge of the condition of the roof. Now the bank is stating a concern. A reasonable solution would be a shared cost in replacing the roof. The seller will close on the property and you will have the use of the new roof during your ownership of the house. If it was in poor condition at the time of the home inspection, you may have already thought about replacing the roof after you close on the home. That expense can be shared so it is a fair deal for both you and the seller. This is why it is important to have a good agent working with you in the transaction.