I need some tips for leveling an older kitchen floor. the subfloor is composed of diagonal planks. my floor joists are not cracked or broken but, they appear to be uneven. I have a post jack under the house where the sag has occurred and I am trying to level the floor but I have also run into the problem of one side of the room sitting a little higher than the other. It looks as if the former owners may have shimmed the beam where the high side is. What can I do? This high side is causing my dining room to slant a little. Any tips would be greatly appreciated.