Hi folks!
I hope there might be some retrofitters out there that might share their ideas on a particular problem. I work on a lot of older homes with stone foundations that are 16 to 24" thick. On at least two sides of most of them the first floor joist is even with the inside edge of the foundation. Sometimes I can put just my fingers into Or shine a light through the gap but I can't get my arm into the space to foam the gap at the top and bottom of the sill beam. Occasionally a window well lets you look down the cavity but you are limited to doing what you can reach. I have been tempted to dense pack the space but moisture is almost always an issue that stops me. Two part foam is very expensive and there is not a guarantee that you will hit your target but you will spend a lot trying.
Anyone have any suggestions? Or do we just let it leak?
Steve/ Starbright Energy Services/Wellsboro

I know exactly what you are talking about. My feeling is that the inner joist is also mostly resting on the foundation, so why couldn't you drill holes in it and blow foam into the cavity. Most likely you'd have to seal some spaces along the run of the joist, but at least it would be insulated. Those spaces are a huge heat loss area, and hard to deal with cost effectively.