Our basement was framed years ago with wood 2x4's and a pressure treated bottom plate. The framer left about 1/2" of space between the concrete block foundation (treated with DryLok or something similar) and the studs. This doesn't really leave any room for any sort of rigid foam board insulation. I would like to use Roxul ComfortBatt insulation as it has some very desirable properties (fireproof, water-resistant, rodent-resistant). However if I use the ComfortBatt:
Do I need to have some sort of vapor barrier between the drywall and the ComfortBatt?
Do I need to have a vapor barrier between the concrete and the ComfortBatt?
VBs are generally a bad idea against concrete, because any sneaking out moisture will get trapped between the two. Were it mine, I'd use the Ruxol and the airtight drywall approach (ADA) to AIR seal, and really do so around any penetrations into the wall. The ADA will let the wall breathe to the inside, since it can't to the outside. Buildingscience.com has some great tech articles on this subject.