I've been getting estimates on closed-cell foam & the cheapest guy wants $6,000 just for the upstairs (walls & ceiling right to the peak)!!!
And remember, my house is NOT that big! This is going 4.5" thick on ceiling & about 3" on walls.
There are 2 types of foam: Closed-cell & open-cell. Open-cell foam is the same as fiberglass as far as insulating properties (R-3.2) & is NOT a moisture barrier or an air barrier. It's soft, while closed-cell hardens like a brick.
I've been researching the stuff for the last 6 months. It has an R value of 6.7 - 7 per inch!! Double regular fiberglass. It's the only way I can insulate this place decently -- it kills 5 birds with one stone: fixes my moisture problems, insulates, stops air leaks, increases structural strength, & deadens sound. Just the fact that it stops air alone would make a HUGE difference in my house!
Maybe I can quit my job & build birdhouses......then attach them to houses, & charge $6K?