I dug up around the parameter of the house to expose the stone foundation. Went down about two feet deep and the plan was/is to re-mortar and cement the hell out of it, followed by putting a weather barrier down and foam board insulation. The stone sections of the house had some obvious leaks, and I am hoping I see some nice benefit from sealing it up. The foundation for the wood frame section of the house, which contains the living room and an upstairs bedroom and bath, was a disturbing mess. Massive gaps in the stones to the point that you could fit your entire arm and/or shovel through the spaces. I could actually reach in and tap the interior floor with the shovel from OUTSIDE the house. Pulled the vertical piece of siding off that covered the separation of the stone section of the house and the "newer" wood frame section of the house. Nothing but a huge gap with no insulation or mortar. I spray foamed that and we will cover it with mortar, also. Looking forward to seeing the difference. But, at the same time, I am really done working on this place. It's great looking, but it has suffered from decades of half-assed repairs.
Wow, I know you've struggled with that house. Sounds like you've found another big problem and I hope fixing that will be another big help. I don't think my wife is on board for all the things I'd like to do here, but we're (me) still working on stuff.
It is almost no surprise. The work you did should make a difference. My neighbor had a similar situation in his 1890's victorian. The first year we all sat in his dining room having dinner, you could feel the wind coming up between the floorboards. Wide pine boards over joists, no subfloor. They were cold that first winter. The oil man was there quite a few times. The following spring, the fieldstone was re-mortared, blow foam inside at the sill. Batt insulation and rigid foam to hold it in place at the rim joist. He removed the floor boards and insulated between the joists. Coal, and then oil was cheap way back in the day.
Good luck with the work. I've had a similar situation, not that its that uncommon. My foundation is really half assed and falling apart, plus a couple ground hog holes into the basement. Unfortunately both are from under the porch so I can't really get to em topside but I fill em back in best I can from below. Minimal insulation in the walls, and the upstairs (cape cod) was a nightmare and had outside air just running right in a few places, down the stairs, and right into the stove room. I just couldn't figure out how I could be so cold sitting nearly arms reach to the stove! I committed earlier this year to tearing out the upstairs and refinishing. Wow what a mess, and the things you uncover (like previous fire damaged trusses that the previous owner hid). Its taken me since spring, and I'm only half way done. Doing foam board against the roof, got the first layer down (R13) and two more thinner layers to go. One big thing I recently realized a big air leak I don't think I can fix. My house is like a tee with a newer half and an 1900 half. There is a small gap between the two, and cold air seems to be getting in there good. I found and sealed up a huge hole the let right in there where the two roofs overlap, but on a windy day with the interior wall exposed, it still feels like a wide open window. Problem is the cavity covers the entire cross section of the house, air could be leaking any number of places, and none of it is accessible. And once it, it is an internal wall between the two halves, so cooling from the inside out. Since I have the one wall exposed in the upstairs, I can insulate it (even though its internal wall but what else can I do?) but that still leaves the other new side and the first floor where cold air is circulating around freely. I so can't wait to get out of this house. I either want a brand new super efficient home to my design, or house I can completely gut and refinish everything.