Hi all, new member here.
I'm in a cold climate (-2 outside as I type this, -30 earlier this month). Over the years (inspecting for 12 years in AK) I've come across frost behind fiberglass insulation in crawlspace rim joist bays many many times. It's a very common thing. My recommendations typically include better detailing of the ground vapor barrier (GVB) to reduce humidity as well as upgrading rim insulation to spray urethane or well detailed rigid foam. Always checking for low perm covering on exterior to make sure we're not trapping moisture. I'm curious if any other cold climate folks out there can share their experiences with frosty rim joists.
Looking forward to being a part of this community. Looks like some great discussions going on here.
Cheers.