Hello, everyone. 

My name is Jonathan. I recently bought a 1.5 story bungalow style home just outside of Baltimore (climate zone 4). The home was pretty clearly renovated from the ground up. 

Lathe removed, new studs/drywall/insulation. New vinyl siding and new doors and windows.

I did notice that it appears to be a balloon frame construction and my rim joist area in the basement is pretty much entirely open with some mineral wool insulation pretty poorly and loosley installed. I can look up into the stud bay above through a void between the subfloor and wall. 

 I’ve noticed that the floor is pretty darn cold above in all of the perimeter areas so I wanted to insulate these voids as I can definitely feel a draft off of the exterior wall. 

My question is: I don’t see where whoever renovated the home installed a vapor barrier anywhere above in the walls. I don’t want to insulate this void below and further reduce the “breathability” of these old walls. I see that it doesn’t look like a vapor barrier is required in zone 4, but does that differ when you’re dealing with a home this old? 

Thanks!