Originally Posted by drhowarddrfine
I have one floor joist in my basement that sits directly under a first floor wall. This first floor wall sits directly in the middle of the 2nd floor bathroom and under the bathtub and is just about dead center in the house. The joist was, perhaps, 1/4 inch lower than the others. I used a floor jack to raise it up and put a 2x4 under it on the foundation wall, next to the sill. It worked but was a heck of a lot more difficult than the other floor joists I was leveling (due to minor termite damage).
However, this one joist has now dug itself into the 2x4 about 1/16 of an inch and my upper floors still show a slight bend near those walls. I presume these walls are not load bearing since they run parallel with the joists.
I thought this supported the 2nd floor bathroom wall because there is a hump in the middle of the door preventing it from closing. Turns out not to be the case and raising the joist may have made the problem slightly worse, don't know.
Even crazier is I have a hump by the back door, which has always been there making the door rub along the carpet. Taking a level along the joists shows they are pretty level but one or two may be 1/16 to 1/8 higher than the others. I thought they should all be the same.
Like I said, I had some termite damage around my rear door and along the plate where this occurs. That is why I raised these joists and put new 2x4s under them.
I hope you understand my confusion and can clear up some for me.
If I understand the layout right this is my opnion of what probably happened... The first floor bathroom wall is not direct load bearing to the roof because it does not line up with a second floor wall. Being parallel with the joists means nothing...although the joists could surely be undersized for this. However, the 2nd floor bathroom walls may be load bearing, you'd have to look at the roof design in the attic. Anyway, the hump in the 2nd floor is more likely to have come from settling of the 2nd floor (especially if the 2nd floor bathroom walls are load bearing). The hump came into play when the first floor partition wouldnt allow the floor to settle there.
I dont know if you have conventional KD lumber for joists but 2x8's and 10's for example can vary in width about what you're seeing with your level... no biggy. A good framer may even shim these up on the sill so the tops are level when building. They also shrink at different rates depending on grain.
I have successfully removed or shortenned partition walls and jacked a sprung floor down from the next ceiling joists or a header but it is not easy and then you really end up using the new shortenned partition wall to hold the floor down until that portion decides to settle as well.
Termite damage and the back door, well you have to get rid of all the rotten wood and then tie new wood in the right spots. I dont have enough info to help with that part.
hope this helped.