found this "vented cantilever" -- the builder used the same vented soffit in the cantilevered 1st floor that is used for the roof eaves. There was just a little unfaced FG stuffed in first but I pulled that aside to see a pretty much air cooled space between the main floor and the finished basement on the windy west side of this home. I reinstalled R19 faced FG, cut blue board to fit between the 2x4's and foamed all the edges and joints before re-installing the soffit -- much warmer at the living room bay window. -- Oh yes, I stuck caulk backer - foam strips in between the top of the brick and the 2 by framing also.
I'll bet a nickel that 99 out of 100 of these that you come across will be the same condition. One I found had a suspended ceiling in the basement, even more gross.
I like the NMEB acronym -- I'm going to use that again. I'll have to look for the pre & post BD nos.(It's been more than a year since I ran the post) This home had a kitchen soffit open to the attic with 7 chimneys ( I mean can lights) and one of the kitchen walls containing said soffit was common to the main bath where there was a fairly good size whole cut in the wall and vanity back for plumbing (the reason why this interior bath with no window and no heating register was leakier than all the other rooms) When I can, I'll post a picture of the "panned return" for the master bedroom -- the one where you can see the backside of the fiberglass tub -- NMEB!
NMEB is why electric air handlers get installed instead of heat pumps...