My fiancée and I just bought an older colonial home, 2 stories, a basement and a walk up attic. The foundation walls are stone and have hardly settled over the years, however the main support beams in the basement that hold the floors up in the center were never properl supported. Now we are dealing with a 3-4 inch sag towards the center of the house on both floors. Everything else seams fine structurally and the previous owner put in temporary support posts but I would like to fix the sag. My question is if I place large Lam beams under the 3 main super beams in the basement and slowly raise the center to level over however long it takes, I’m assuming at least a few months, Can I safely correct a sag that severe?