Ok, this is probably a really really stupid question but I need clarification.
Can you use a spray foam insulation (such as Icynene) with a radiant barrier?
In what I've read regarding spray foam, you apply it directly underneath the roof rafters to create an "envelope" in your attic. There are no roof vents or soffit vents.
With radiant barrier, you leave an air gap (if insulating the rafters) and there are soffit vents and roof vents.
So this tells me if we applied spray foam to the underside of our radiant barrier coated roof decking, we've just wasted the extra cost of the radiant barrier decking? Plus our brand new roof complete with ridge vent is now a waste.
I really like the idea of using spray foam. I'm wondering if we would gain any efficiencies by just applying it to our exterior walls and using regular blown cellulose on the attic floor? And then upgrading to more insulated ductwork?