This is my first post here.
I have a ca. 1870 house in NH with an attached small barn. The 6x8" sill on the barn is rotten/absent on three sides due to grading problems which we recently corrected. The whole building has dropped several inches on these sides where the sill is now gone. A handful of studs are resting on the stone foundation, which is what's keeping it up. On the fourth side where the sill is sound we previously formed up and poured concrete over the rubble stone foundation to stabilize it down to about 1 foot below grade.
Now it's time to deal with the remaining three sides. I've done a good deal of carpentry restoring/renovating houses but never a sill replacement like this where the building had to be lifted. The barn is 22x18 and attaches to the main house where they overlap for 6 feet on one of the 18 foot sides. It is 1.5 stories, 2x4 (actual dimension) balloon famed with a second floor that we use for storage. The first floor framing is shot from someone who used to park a car in it. It has about 5 layers of bouncy flooring, and a crawl space underneath that's about 12-18" deep. Parts of the floor framing are just resting on the ground.
Here is my plan:
1) Rip out the existing floor on the ground level.
2) Refasten the second floor joists where they attach to the studs.
3) Jack up the building on the rotten side to partially level it by pushing up on the second floor framing using a beam of some sort, being aware that it's still attached to the house and that it has a metal roof (standing seam). So I can't lift it very high without making new problems.
So here's where my plan gets a little vague....
4) Cut off the rotten bottom of the building. I think of this like hemming pants that are too long. I guess we just take off siding and sheathing until it looks solid again, snap a level line, and cut it off with a sawzall?
5) We can't afford to excavate and pour a frost wall, so form up and stabilize the existing foundation with concrete as we did on the other side. Bring the new concrete wall up to meet the newly trimmed framing or else somehow extend the studs back down to their original level.
6) Insert a new PT 2x6 sill plate, fasten with anchor bolts.
7) Lower the studs onto it.
8) Replace the floor.
Does this sound like a reasonable approach? I'm 95% sure that the first floor and its framing aren't salvageable. Removing them will make jacking the building much easier.
1) What kind of beam would you all recommend to lay across the second floor joists to push up on?
2) How many jacks and of what size do I need?
3) Should I raise the height of the foundation wall to meet the trimmed off barn wall, or extend the studs down to their original length. The latter approach will make re-installing the floor much simpler.
4) How do I get the new sill over the anchor bolts if there's not much clearance under the trimmed studs?
I'm going to try to post a few photos if I can. Thanks to any and all who respond.
Back side showing the one 'good' side that's been stabilized on the right, a section of the original foundation, and the corner where we pulled out the loose foundation stones to have a peek inside. No weight was bearing on them.
The back corner. The sill is just gone here. There should be two more courses of claps where the void is. You can also see one of the floor joists sitting on the ground inside. Yes, that appears to be a laundry drying rack that's falling out of the wall. The adjacent wall to the left is 22' long and has a bad 6x8" sill. It's not totally absent like this section, but you can stick your finger right through it. The top course of the stone foundation was removed here to allow us to look under the floor since no weight was bearing on it:
The view from the front. It's hard to see, but the barn door drops several inches from left to right. The corner shown above is the one closest to the yellow skid-steer loader: