nealtw

Some what below the floor height let in a 2x10 into the studs so it is flush with the studs and bolt 2 more onto that and you have a beam to lift with. Between the beam and the floor add 12 x12 blocks of plywood about 2" thick and bolt them to the studs to stop the beam from rolling. Add 2x4 braces from the outside of the beam down to the studs near the sill to keep everything straight, and braces from lower studs to the floor joists for insurance.
Everyone worries about lifting a house, that it would be unstable, all we did was jack one jack 1/8 or 1/4 and put in spacers and set it down and went to the next jack.

oldhome

If you are talking about studs, you must have a pony wall above grade? I have 2' of brick above grade, the sills rest on the brick, and the floor joists notch into the sills.

Sounds like you braced everything, which is something I'm mapping out in my mind right now. I have less framing in the basement to brace to, but I should still have some options. I will probably block between the joists to stiffen things up.

nealtw

I missed the part about the brick , sorry. Just as well, cutting into all those studs would have been a problem anyway.
Keep in mind the house we worked on was 8 years old and the owner was the builder and a building inspecter, he had the plans and knew where the bearing points were and how big the footing were. We planned the job for a year. We talked the a few engineers for pros and cons and only got cons from them witch we used to identify problems to solve. I hope others will join in here to help identify problems for you to solve or help you solve them.
I suppose you could remove some brick and jack up the sill as it is 6x6 but we haven't addressed the foundation condition or the footings, perhaps the first order would be to consider underpinning the jacking points.
Keep in mind when you have solved all the known problems the big one is just around the corner, what about porches, decks, stairs, chimneys, plumbing and of coarse rot?

oldhome

All good concerns. The good news is that the wood is in reasonably good shape. There is the normal amount of joist & beam checking, and the spots with real issues have been identified. A section of beam has been identified for partial replacement, but anything suspicious already has a post. I will probably run a length of timber below the one really stressed beam.

The subsidence of the foundation has happened over 100 years, and a number of contractors including two structural contractors have seen the stone foundation and pretty much said "not too bad, I've seen a whole lot worse." I wasn't really thinking about using the foundation as a lifting base, I was thinking of building up cribbing inside and out and running needle beams between the two. If I do put a jack on the foundation, I will only do so on the more stable wall.

I figured that I would mortar up the most weathered stone walls to help them hold together when they get unloaded. Cleaning out and mortaring the gaps seems pretty straight forward, but I wonder about using far runnier grout which if introduced through gaps up high, will go wherever gravity takes it. It might do a better job of binding things up. Only hesitation is that I've often heard that old stone foundations really want softer mortars with more lime, because stone walls relying on a mortar that will give and put up with the settlement that occurs over the years, and because it will let water pass which alleviates the lateral forces of hydrostatic pressure.

Plenty to think about, but I'm happy to hear more about what I might be forgetting.
Believe me, you won't find a guy more grateful to be told that he's wrong.

nealtw

I know nothing about stone foundations, I hope others will be along for that discussion.

oldhome

Can anyone comment on the risk of the stone foundation giving way when the the house is raised and its compressive pressure on the foundation is removed? Does it take a disaster of a stone foundation for this to happen or is it a common concern?

nealtw

I am surprized no one has anything to say here.

oldognewtrick

I'd suggest calling a structural engineer if you have any questions about the integrity of the foundation. It will be money well spent.