Couple points:

I will have to disagree with the use of pink fiberglas between the sheet metal.

In my opinion, you are setting yourself up for that to become soaked with moisture as warm (moist) air seeps into the space,

Furthermore, in the summer, accumulated moisture from the rocker panel areas will go up, and be trapped there.

I studied the cost - benefit of the fiberglass, and decided to only use them "bagged" in water resistant bags (freezer bags).

They were used inside the vehicle (under dash), and also in side and rear doors where fiberglass worked well ---- also used up my scrap fiber mat (recycled from under the rubber mat in the factory installation).

They were dried, and reused as insulation in the doors after being individually wrapped in plastic bags (to prevent moisture build).


I did study using the bubble / foil insulation.

It was rejected for the following reasons:

I wanted an operating temperature range to -30F up to +90.

The foil bubble wrap have virtually zero insulation value in and of itself except as a radiant barrier.

Fiberglass, on the other hand, is a function of thickness, roughly R7 per inch.

Furthermore, fiberglass is an inherent noise deadener ---- which may not matter to you with a V8, but to me with the diesel, it is a major concern.

I considered using rigid foam on the floor, and rejected it in favor of fiberglass because it "packs" and I also put copious amounts of it on the tire well area --- raising it to R10 with about 1" in critical areas.

On the floor itself, it consumed slightly less than a 1/2" foam board, because it "compressed" into the ridges in the floor.

Now, in my walls, I added a 1/2" furrier strip to the van's ribs, resulting in a wall thickness of close to 1" on top and sides.

What I found in winter testing this year is that level of insulation is truly good to -30F.

Though the weak spot is the "cab" and back windows are cold... and condensation is now a major issue ---- icing on the front windows is awful.

I ended up with a furnace of close to 18,000 BTU, which on max power, will warm the van interior (even with the front window uninsulated) to a toasty 70F or higher at -30F outside.