rafter insulation under skip sheathing in unvented assembly

I’ve seen the recommendation that there be no air gap between the sheathing and insulation when filling the rafters for an unvented assembly, but I missed the explanation on why… I’ve seen the recommendation that there be no air gap between the sheathing and insulation when filling the rafters for an unvented assembly, but I missed the explanation on why…Read MoreGreenBuildingAdvisor