I see decks installed like this all the time. There is a deck at the end of my street where they put the joist hangers over vinyl siding, made worse by the fact that the vinyl is the fourth or fifth layer of siding on the building[:-bigeyes I have pictures somewhere of a deck done like this by an engineer, I've posted them here before, he had me over to look at it because he couldn't figure out how to flash it after he built it[:-banghea Rob, you were there. If the deck can be made servicable and your clients are really strapped then tell them how to fix it, but be certain that they understand it's a bandaid and not a permanent repair. If it's relatively new and not too terribly screwed up, then a competent carpenter should be able to prop it up and install a properly flashed and anchored ledger along with some diagonals to stiffen it and the stair. If it's old and in need of lots of work beyond that they will be further ahead to replace it. I think it's a bad idea to put new work on an old deck, there's very little cost savings and the hard to fix stuff is still old.