These combine a bit of trapped air technology along with using the foil material to reflect radiant heat.
Foil backed bubble wrap insulation.
Double bubble reflective foil insulation 24 inch x 10 ft roll industrial strength commercial grade no tear radiant barrier wrap for weatherproofing attics windows garages rv s ducts more.
Most metallic bubble wraps are about an r 1.
Foil faced bubble wrap is composed of either one single bubble or two double bubble layers of mylar air bubbles sandwiched between two metalized surfaces.
This effectively acts like a mirror reflecting heat back to where it came from.
Some insulation materials don t work 100 on trapped air.
Prodex total is composed of 13 64 inch approx.
These are the multifoil materials which include foil backed bubble wrap.
I have heard some say that the insulation could be installed loosely to maintain the gap.