Should spray foam insulation be applied directly to the underside of a roof that has used OSB with a radiant barrier (combo type product)? If it has already been done, should the builder and insulation installer have known better? Should the foam be removed?
I can’t speak for the builder or installation installer or to the level of their understanding of radiant barriers and how they work. The result of affixing any surface to a radiant barrier is to negate its performance capability — radiant barriers must face an air space in order to reflect or not emit heat. I think there are other simpler solutions to your situation. You could install a radiant barrier on the underside of the roof trusses. If that isn’t feasible and you have mass insulation on the floor of the attic, you could install a perforated radiant barrier on top of that. Whether either option is advisable depends on where you live and how much insulation of all types you already have.