I do not know a lot about thermal imagining but 65% humidity would make any porous material such as drywall damp, thus the temperature difference would not be all that great. I am guessing but if the humidity was about 65% for several weeks, drywall moisture would be from 8-14%. Of course considerably higher during the summer months.
Sean,
You could also try other IR forums, like Snell’s IR-Talk http://http://www.thesnellgroup.com/irtalk/
If they can’t give you the exact answer you’re looking for, no one can.
Cool! Thanks