AtticFoil Radiant Barrier Foil Insulation | Don't Use Bubble Foil Type Products In Attics - There Is NO Additional R-Value When Stapled Up. @AtticFoil | Uploaded February 2013 | Updated October 2024, 3 hours ago.
atticfoil.com/index.php/knowledge-zone/knowledge-zone-attic-foil-vs-other-products
Ed shows why stapling up products with fiberglass in a vented attic does not really produce any additional R-value. All foil products will reflect the heat, but you want more R-value on the floor of the attic.

This even applies to OUR Foam and Foil products at www.BlueTexInsulation.com.
They are intended for metal buildings where you want to reflect heat AND create a vapor barrier.