Originally Posted by nealtw
His wall is mortared, why would you not treat it like brick?
Well it is 100 plus years old and lots of this mortar was pointed in from the inside and outside to seal it up. It is an unknown.
The only way I would trust doing something like this DIY. Stay with me I’m going to paint a mental picture here.
First crib the joists and jack up and take the weight of the house mostly off the foundation in the area where you will be working. Then drive steel under the lowest stone and past the outside of the wall a good 2 feet. steel could be ½ x 2. After getting an area large enough to work on done then drive a piece 3” angle iron in on top of the steel. I would space the steel every foot. I would then weld the angle to the bars I have driven in. now I would build some 45 degree bracing to run from pockets in the floor backed up with a good foot and weld or bolt that to the angle. Now you have a section of the wall braced in place from falling and the rig you just built is only holding the stone not the house as well. dig out that section and place footing and build wall. move over 4 foot and repeat.
The problem in doing this is you assume the bottom row of stone was laid flat. Every time I have ever worked on field stone I always found they found some bolder they put in first and who knows if they didn’t dig it down a little to get that one set in. with stone there is no reason to start with a flat footing as you correct all the way up the wall and end flat.
I have seen a lot of old places taken down and when they get to the basement walls they roll them in a bury the stone. It never looks like it is too hard to do.