The kitchen floor was a little saggy. Even after replacing a rotten sub floor, we've installed new joists to raise and support the sagging kitchen floor. We used a jack to raise the floor and now the floor is level.
It's official, we're now 100% iron-deficient. All cast iron have been removed from this 100 year-old house. Everything has been replaced by copper and PVC - they're easy to repair and not subject to corrosion.