[BRENT in 10-uh-C]

Tom, the Dynamat is not an insulator. It is a sound dampener with no real R value. The big box stores will sell a bubble foil insulation that can be used. Rockwool is another that is good. It is water resistant and as soon as it dries, it is back to normal R value. The jute works well too and can be glued to the foil insulation. Use Weldwood Landau & Top Adhesive for this.