i think the one Mark talks about is this
Rmax Thermasheath-3 1 in. x 4 ft. x 8 ft. R-6 Polyisocyanurate Rigid Foam Insulation Board
http://www.homedepot.com/p/Thermash...-Rigid-Foam-Insulation-Board-787264/100549260
but they also have 2 inch thick board for 28.50, and for my 2 car garage door, 1 4x8 is simply not enough, i had to get at least 2 more board to cover all the area.
Rmax Thermasheath-3 1 in. x 4 ft. x 8 ft. R-6 Polyisocyanurate Rigid Foam Insulation Board
http://www.homedepot.com/p/Thermash...-Rigid-Foam-Insulation-Board-787264/100549260
but they also have 2 inch thick board for 28.50, and for my 2 car garage door, 1 4x8 is simply not enough, i had to get at least 2 more board to cover all the area.