My wife and I purchased a house with a detached 3-bay garage. On the back side of the garage the previous owners hacked in a 16x30 ft lean-to. The joists are 2x6x16 treated and set on Simpson joist hangers on both ends on 16" centers. The one good thing they did was use 6x6 posts and spanned no more than 10' the long way and 8' the short way, so if you imagine looking at it from the front, there are four posts 10' apart on the outside, and other 4 posts 8' behind those, and nothing under the ledger board attached to the garage. The top ledger board from what I can tell is screwed into the studs framing the garage. This whole thing was put up with regular deck screws, no nails. None. All the joist hangers are up with regular 3" deck screws. This was pointed out during the home inspection and the inspector said he felt like the structure was stable an safe but that it could be strengthened to make it safer. As of right now, this structure shows absolutely no sign of failure. My best guess is that it's around 5 years old. There is no sagging, all the joists are securely fastened. The roof is shingled and I got up there and bounced around and it feels solid. Obviously I'm concerned about the longer term implications of the structure because I do keep my mowers, trailer, and other equipment under it. I'd also like to use one of the 10' sections for a dog kennel one day. I cannot afford to take down this structure and do it correctly right now, we just sunk everything into the house. I would like some ideas for strengthening the structure so I can use it long term - if possible. One idea I had was to replace the deck screws in the joist hangers, one at a time, with Simpson structural screws approved for joist hangers. My concern there is that the replacement screws might not get enough "bite" since a hole is already there, and I was also afraid a nail would be ineffective in that case as well. I am also planning to put some posts in right next to the outside garage wall to support the attached ledger board, and then run some members long way bolted to the posts to support the underside of the joists on both ends and in the middle. Any comments here would be greatly appreciated.