I am trying to find out what steps I need to take to fix my sagging floors on the first level of my home. I have a tri level and when you walk into the foyer you can see the floor separating from the bottom stair and you can feel the floor dipping. The sagging is getting worse and its also in the hall going into the family room on the same level. Should I hire a contractor or have an inspection done first?

I live in the South Suburb of Illinois.

A contractor is (or should be) an expert in HOW to do things, but not necessarily WHAT things to do. An architect (at least a good one) is an expert on WHAT to do, but not necessarily HOW to do it. A structural engineer is the same. Together with a good contractor, the design professionals make a great team.

Have your house examined by a good architect or a structural engineer, to determine what must be done, and THEN let the good contractor DO IT.

That is the best way to proceed.