I currently live in on the top/third floor of a condo on the outskirts of Chicago.
The building is fairly older, and when I moved in about 5 years ago, I noticed that floors drooped towards the middle... it never bothered me at first, but I think it may be getting worse (or I just notice it much more). I never bothered to find out what was under my wood flooring, but I had to pull up some boards for repair, and found out it is concrete. There is a crack where I pulled up the boards...
I guess my question is, is the concrete slab the unit sits on part of the owners responsibility, or the building/association?
I know the wood flooring is my responsibility, but if who ever built the building made them unlevel; or the building has settled over time, wouldn't this be the building...?