Under Construction

Insulation

We were more concerned with the van getting too hot than too cold. Therefore, our design sacrificed 1/2″ of thermal insulation to build in a radiant barrier. We, along with the construction industry, were leery of creating a two vapor barrier sandwich. The metal body being one and many people create a second one on top of their insulation. This will trap any moisture that gets caught inside the sandwich and not let it dry out. Not good. So we did not create a vapor barrier on the inside of our insulation. In any event starting from the metal body inward this is what we did:

1. Metal body
3. 1/8″ of self adhesive foam and foil duct insulation stuck and rolled onto the inside of the metal body. This will help prevent moisture getting to the metal body. It also provides a radiant barrier in that the foil surface facing inward into the van will only radiate around 3% of the heat that reaches it. This is where the highest temperature gradient will be found in the system, where the metal skin is heated by direct sun light.
4. Next we created a 1/2″ air gap. Radiant foil barriers only work if there is an air gap next to the foil. We did this by glues small pieces of 1/2″ polyiso to the duct insulation.
5. We then stacked as many layers of 1/2″ polyiso onto the small pieces of polyiso as appropriate for the space between the metal beams. The outer most polyiso was oriented so that the foil surface of the polyiso faced the foil on the duct insulation. This will theoretically reflect 97% of the 3% of radiant heat being emitted by the outer foil surface. The inner-most layer of polyiso was oriented so that the foil radiant barrier faced inward. This provided an additional radiant barrier anywhere the interior walls left a gap and did not touch the insulation.

On the floor we just covered the bottom surface of the 1/2″ plywood flooring with self adhesive duct insulation foil down. It will at least break the thermal bridge from the top of the corrugated metal troughs to the wood and a radiant barrier where the bottom of the corrugated metal troughs don’t touch the duct insulation. We factory ordered the plastic floor covering with the van. We used it as a template for the 1/2″ plywood flooring and then place it on top of the plywood. Laura complains because the textured surface doesn’t sweep easily. If the sun shines directly on the plastic it will expand and bubble up very slightly as there are so many places where furniture is attached through to plastic into the plywood.