Originally Posted by nealtw
Bud: You may get away with leveling a floor with a wall built in the basement, but lifting structure is not a good idea. You may have got lucky but you are putting a lot of faith in the strength and thickness of the concrete and the soil below it.
My thoughts were the settling had stabilized a good 50 years before I was born based on the cracking in the horse hair plaster and window and door framing shifting. The house was twisted and swayback here and there but wasn’t actively moving in very many years. Given a $100k I might have lifted the home and added a poured proper foundation and then another small fortune to correct the rest. But George Washington never slept there although he did sleep at an older place down the street. So given what I had I did what I could and felt safe with the house. I wasn’t intending the stud walls or the poured floor to carry the weight of the house. I did frame it 12’ OC with a double plate but the purpose was more to take the bounce out of the first floor and a little of the sag without shifting the whole structure upwards.
In my house the field stone foundation was about 4’ wide at the bottom and tapered up to about 3’ at the top. At that point framing switched to wood a 12x12 timber around and 12x12 cross in the middle. The middle cross was mortised for the 4x12 floor joists. All that cutting into those timbers made for places for splits to propagate. Some of the splinting I did closed those gaps and lifted the joists, and in the process helped some of the floors above.
The big question the OP has to answer is the house stable or is he seeing signs of the past repair and still seeing things are not plumb and square and thinking the first repair was not done properly. They may have went as far as they dare go and started hearing cannon fire above and stopped. There are many clues he could look for if the foundation is still failing and in that case I do agree just jacking it back up won’t solve his problem and could even make it worse. If I had to guess based on it standing 116 years I would guess foundation isn’t recently starting to sink, but that isn’t an option to rule out.
The idea of paying a structural Eng. to evaluate the problem is not a bad idea and have him recommend a procedure from there. In my town in the city there are 1000’s of century old houses and they all are suffering the same old age problems. I never hear of any falling in and quite often it’s the new construction that goes down under snow loads and storms. But again I wasn’t recommending any fix only telling what I did and how it worked out in my one case.