Hi all, I’m pretty new to this insulation stuff so I appreciate your patience. I’ve also tried searching but I didn’t have any success. I purchased a 1952 construction mid-century home and we are in the process of doing some thoughtful updates to the home. The exterior walls are apparently two 3″ concrete masonry unit walls separated by a 2″ air gap. The interior side of the exterior walls are, for the most, not framed out so most are the walls are exposed concrete. It’s a neat feature but I don’t believe this offers much insulation. We’d prefer not to frame up and drywall over most it if we can avoid it. I was wondering if spray foaming the air gap between the 3″ CMU walls would provide reasonable insulation value or if it might be inadvisable for some reason. We’re in the Denver, Colorado area, so it’s not a wet climate but it’s not clear to me whether it might be a reasonable move. Again, I’m a total newbie to this stuff so thank you for your help and patience.