what kind of foam is getting installed?
the difference in R value would be the thickness of foam applied.
make sure it is closed cell foam. open cell acts like a sponge.
One vendor's foam I've been using claims to be R7 per inch of thickness.
I would jack up the existing floor joists. try to level as much as you can. insert yellow glue into the cracks and Screw a grade 5 self threading lag screw into the bottom of the joists near the splits. attach mending plates over the splits. and then glue a new, larger joist next to the existing...
in one corner of my house, there was a constant exposure to water. there was an outdoor faucet in this corner and the down spout also contributed to moisture here. I removed a garden hose holder, which looked like it just kept redirecting moisture onto the walls. in any event. the sill in this...