Our home is almost 60 years old. The floors in the center of the house are sinking as is noted by twisting paint at corners of a room and slopes toward the center of the house. I can also see the sub flooring buckling at the seams where there was no problem 3 years ago. We are having an addition put on the front of the house and will need to redo all the flooring throughout the main level. Can we correct the floor sagging and if so how? Thanks for your help.