For basement, crawl space or anything that holds a lot of humidity, it is best to spray foam
with 2lbs density polyurethane foam. Some places you can get away with fibreglass insulation, blown-in cellulose or blown-in fibreglass. Like in a attic where you would have all
kinds of room to install a thick amount of insulation, I would not spend money on
Spray foam insulation being that its so expensive. If it would be a cathedral ceiling, well then I would go ahead and spray foam because you don’t have enough room for proper
insulation.
