I have a 2 story balloon frame structure that has the unfortunate problem of sinking walls (2 of the 4 exterior walls), which has the side effect of unlevel floors. Parts of the second floor are up to 1' below the rest. The structure itself is sound, no rot, warping, or other common problems other then the sinking walls.

I am thinking about putting a post frame structure under the second story floor and jacking the whole structure up slowly over a couple month time frame. I am needing calculations to figure out the size and spacing of timber to use. So far I have come up with a 10'x10' grid of posts with 4x12 runners (sistered 2x12s) running perpendicular to the floor joists with a 4x6 or 4x8 tie between the columns running parallel to the floor joists. The columns will each sit on a concrete footing (which I also need to find the size of)

The only numbers you need should come from a phone book. Call the company called
Ramjack, there moto is well never let you down, sounds great for you,
Also a sound struture doesn't sink either Foundation Repair Systems – Ram Jack (http://www.ramjack.com)