The cellulose in my attic weighs around 15 pounds per square foot, we have over 2,000 pounds of insulation in there!
I would only use spray foam to air seal your attic, then use cheap blown cellulose insulation to add the bulk of the insulation value.
As far as weight of foam on the dry wall, the only issue that I see you having is spraying to much foam at one time in a way that it pushes on the dry wall as it's expanding and pops the dry wall loose, but at the same time it will act as a glue and minutes later it will be cured and gluing your whole house together.
|