@transcendentape Alrighty, I can't help it - you said earlier that it was the act of adding air conditioning that led to mold problems. Is that correct?
It's not simply that the attic is /there/ it's that there is now a place being maintained colder than ambient temperatures near to it.
Now, as far I as can tell, homes here are built like highly-insulated boxes. That box than gets a roof plopped on top of it.
I truly don't know what you mean by "it's easier to insulate a wall"