[DangeloInspections]

Originally Posted by Arctic Fox

what would likely cost be if you have it done when you get a new roof?

thanks

The cost would be moot, because it simply would not work and could actually hurt, if you are referring to sandwiching the foil between the shingles and the sheathing. If you are thinking of replacing the sheathing with new sheathing, it would still be very costly.
Here is a link;
Radiant Barrier Under Shingles Scam | The Radiant Barrier Guru
Can I use AtticFoil(R) Directly Under My Shingles? | AtticFoil(R) Radiant Barrier - Do-It-Yourself Professional Grade Radiant Barrier