Our Boned Logic Insulator came in 4' x 75' rolls. The space between the bus ribs is about 25.5" wide. Rather than try to cut the insulation to fit the gap, we decided to go with 24" wide strips and fill the remaining .75" gaps with spray foam.

One more advantage to using foil-faced insulation -- space aliens won't be able to read our thoughts! ;-)

After applying Insulator to the side walls, there was just enough room for 1" rigid foam insulation. This R-Tech Insulfoam is made with no CFCs or HCFCs, and contains no formaldehyde. Also made in Arizona (and elsewhere).

The gap was filled with DAP expanding foam spray insulation.

1/2" Rigid foam board has just enough flex to follow the curve of the roof without snapping. Careful cutting allowed the panels to fit securely without the use of adhesives. Two 1/2" panels were used to make a total of 1" of foam insulation.