When it comes to straightening a garage, I have not seen really anybody to really do this type of garage repair, especially when they are leaning one way, and they are leaning another way. The lot of times you might see a garage roof that looks like it has a sag along the top of the roof. Sometimes you will see the foundation knocked off the concrete slab. Also, you see might see the walls at the top with a bow where it is sticking out, kind of rounded. These are tell-tale signs that you have structural damage. Sometimes this will happen because the carpenters of old, what I mean by that is the carpenters from the early 1990s, did not use proper wind bracing and collar-ties to keep the garage secure from shifting and sagging.
Another reason you might see a garage with a big sag in the roof is a new garage door was installed and in order for them to put a new garage door in, have seen this over and over where they cut the lower rafter ties in order to install a new garage door. When they cut it, they 95% of the time will never replace it, which causes the garage sides to blow out.
