Posted by Freddie Mac (148.63.162.153) on October 02, 2009 at 22:47:06:
In Reply to: Attic Insulation posted by Janet O on October 01, 2009 at 22:02:25:
I think the foil is supposed to be a vapor seal of sorts. A vapor seal goes toward the heated side, to reduce moisture flow into the insulation, where it will condense as it cools.
However, if there is already a vapor seal, the it can go up with the idea that it may reflect some radiant heat from the sun.