DURING
So... The building is tipping over, entirely unsafe, completely unusable, freezing cold (it's January at this point)... and I have no skills at all.
So I read and read and read... and talk to barn owners... and builders... and Amish barn builders... and I figure out the order of operations goes like this:
1) pull it as straight as possible
2) fix posts/foundation/sill
3) everything else
Interestingly, the "everything else" is what gets the ooohs and ahhhs from most people, whereas the "pull it straight" and "fix posts/foundation/sill" was where all the really cool and hard work ocurred. Shrug.
I used 6 come alongs to pull the building over a 1/2 foot straighter. It still leans, but it's much better now. This was a scary and noisy process. I left myself multiple exit routes at all times, wore safety gear galore, and just went very slowly. A building this old isn't real keen on being moved, but move it I did.
After the building was straight and braced to high heaven, I lifted each rotten post in the building and spliced in good wood on top of a cement footer. To dig the footers I had to first unstack huge foundation stones, then mix and pour. Meanwhile the building is suspended on jacks for a few days at a time. I had NO helpers at all, so it was relatively slow going.
The center post in the building is the most important post. Mine was completely hollow. So I had to support all the way to the roof with jacks, and entirely replace it.
Also shown here is a lifting rig I built to lift the front of the building. This worked nicely, I would use this method again.
Framing the back wall (the wall that once swung freely when kicked) was validating step in the process. I added two intermediate posts where there were previously none... over a 25 foot span!!! This allowed me to suspend a sill between the posts and build up from there. The sill and framing in this area is not structural as the posts do the work, but they definitely add strength and give me a place to attach sheet goods.
And finally, I contracted out one step in this process... the floor.