We have 2 x 8 exterior walls with 2 x 4 staggered stud framing. Standard plywood sheathing with hardie board siding. Full 2 x 8 on plates and at openings so we are a bit surprised to find the same frost pattern on the wall as the rest of the standard framed 2 x 6 framed houses in the neighborhood. There must also be a dewpoint factor involved here? This isn't what I've been led to believe in the building science classes I've taken... Any gurus out there that can shed some light on this?