I live in a house built in the early 1900's. The dining room, which is in the center of the house, sags enough to where you could set a marble in the middle and it will always roll to one side.
The main beam running the length of the house in the basement has a support jack installed, but is it dangerous or detrimental to the property to have so much sagging in a particular room?
I had to have a structural engineer take a look at my house before I closed on it. I have a roughly 1" sag in the middle of left half of my house where a pole was removed. According to the structural engineer this would not get any worse and is "safe", aside from any annoyance it causes. Yours may be a different situation, so I'd recommend having someone come out and take a look. I believe mine ran me about $450.00 for the consultation. Money well spent to know I won't fall through my floor at night.
If you own the home, definitely make plans to re-block it. If your renting, pressure the landlord a little bit to get it re-blocked. I wouldn't want to live in a house that could possibly cause accidents because of rotting floor joists.
