My father's house has an attached 2nd floor porch of substantial size that is leaking. The inside is plywood, the outside is tin. The roof is leaking at some of the seams. There are no visible holes. How would you suggest repairing this roof? Sealing the seams alone would probably not be enough. The roof is 42 years old; in good condition except for the leaking areas. The seams are visibly open at some places. How do you suggest repairing? If repair alone is not enough, what type of overlay roof would you use?