Air migrates from warmer spaces toward colder spaces and insulation is designed to help prevent or at least slow that migration.
Fiberglass attic insulation vs reflective.
The key to using reflectix properly is that you should take a little time to understand how reflective insulation works in the first place.
The reflectix site provides a great range of information about this and about how it differs from other types of insulation.
Radiant barriers reflect radiant heat.
Remember traditional attic insulation has r value that works to slow conductive heat.
Which is better will depend on the topography of the specific roof you re insulating.
The radiant barrier resulted in roughly 4 times more savings than the added insulation.
Next i compared adding an additional r 19 to my existing r 19 level of attic insulation vs installing radiant barrier and the results actually surprised me a little.
Radiant barriers and reflective systems.
What is the right insulation for an attic.
If your attic has a lot of nooks and crannies your best bet may be to use loose fill insulation made of fiberglass or cellulose.