We are going to dig up and completely relay a floor in our house that has sunk (when first built 60+ yrs ago) and i was wondering what thickness the concrete needs to be, the hardcore needs to be, the sand needs to be, etc and any general tips/advice on how to it.
Before going threw a complete tear out. consider a concrete leveler product. Their are thin self leveling concrete products used for flooring that can be poured over the slopped floor. These are available at many home stores. If unsure contact a flooring contractor and get their opinion of your situation.
Make sure your gutters and downspouts are all in working order, and no water is being forced up the structure. Excessive settling is many time the culprit of water erosion.