I just moved in a couple months back and noticed that this wall was a lot thicker than expected, lots of unaccounted for space. I was honestly expecting to find a body in there :P glad I didn't!
The space is only accessible from above, between the joists in the ceiling. I stuck my arm over the wall with phone camera in hand.
The wall is obviously supporting the joists, but I don't know why there are two cinder block walls with about 1 or 1.5 ft between them.
Has anyone seen this before or have any idea why it was done?
I'm planning to increase insulation and do air-sealing, but have no idea how to deal with this space!? One of its sides is an un-insulated exterior wall :(
Video (spider-web warning!): https://www.dropbox.com/s/vvb3f9qdh0eat2e/VID_20190824_122226.mp4?dl=0