I have a 15 year old, 2 story home that shows signs of floor sagging (about 1.5") in the center of the first and second floor. The floor structure consists of joists utilizing wood studs on top and bottom and metal hangers that run on each side of the studs in an alternating diagonal pattern. The basement was recently finished by the previous owner, but the laundry area still has the floor joist area open. I've looked into the closed cavity over the finished basement area and noticed why the sagging has occurred. At that point the upper section of the metal hanger has bent out from each side of the upper stud in the joist and the upper stud has bowed. The lower stud is still level and the metal hanger is still connected.
I know I'll have to cut out a section of the finished ceiling to access the area. My question is how or can I jack up the upper stud without cutting away or disturbing the lower stud? My plan was to get the upper stud back in position, hammer the metal hangers back in place, install wood blocking between the upper/lower studs and attach a metal plate or thick wood panel (at least 36" long) to both sides of the upper/lower studs to stiffen the area. The problem comes in that I'd have to remove the jack to install the support structure. Any ideas on how to work around this problem? Thanks in advance.