Anbody ever use this stuff? Prodex insulation Does it work?

It has an R value of 15.67 with a single layer. I think it would work great. Most house walls have an R value of 6. It will not eliminate all the heat in your garage but it should cut it down.

It would work even better if it was on the outside.

The metal surface is designed to reflect most of the radiant energy.
Andy