Difficult Rim Joist Insulation
Hello all, I'm in the process of remodeling my basement, and have been doing significant research on insulating. My hang up is the rim joists. Mine overhang the house by about 6 inches all the way around, leaving a pretty deep cavity to deal with. I understand the concept of cutting XPS board and sealing them in. Currently, they are all stuffed with fiberglass, so I understand I have to remove it, install the XPS, and reinstall the fiberglass.
On the one wall (garage on opposite side) that the joists run parallel to the block wall, I have about 1.5" of space between the block wall, and the last joist. From the last joist inside, perpendicular framing members extend out to the actual rim joist, which leaves me with a bunch of rim joist cavities that are inaccessible, and have fiberglass in them that I can't get out. I assume they were stuffed with the fiberglass before the first floor was covered.
So, how do I go about sealing up these cavities? Also, am I right in assuming I have to cut XPS for the bottom of the overhanging part of the rim joist cavities, as they contact outside air?
For the record, I'm not SUPER concerned about saving every dime in heating costs, but more concerned about moisture from air movement and condensation. Thanks in advance.