Fiberglass Insulation

[cleonard]

I'm sure that fiberglass would work, but for this type of application the foam is better. Most of the cargo trailers has a one inch space for insulation and the pink or blue extruded foam will give R-5 in that confined space. It's hard to find fiberglass insulation that thin and I'g guess that it would be R-2 or maybe R-3 at best. Another positive for the foam is strength. If you take the time to get a close fit and glue it to the skin you can add a lot of rigidity to the trailer.