It was time to add some insulation to the ceiling of the van, now that with the Murphy bed installation, access to the ceiling is closing up.
I already made the decision to use primarily Poly-Iso and Denim insulation and started to fill the ceiling cross-members with Denim. The cross-members allow for approximately 1-1/2 inch insulation, when you follow the curvature of the roof.
Poly-Iso is fairly rigid and not bendable, so I used three 1/2 inch layers to fill the area between the beams and I still needed to add cuts to the insulation, to make a better fit.
The panels were glued to the ceiling with 3M 90 spray glue and some of the seams covered with a very sticky HVAC tape. While this all will substantially reduce the heat build-up inside the van, I know that during the hot and humid Florida summers will wreak havoc on the interior temperature control. There is likely a greater benefit in winter, when it can keep the cold out long enough, for the early sun to heat up the van.
A good alternative to the Poly-Iso is Thinsulate, an automotive bat insulation, that is easier to install. It is pricier though and has a lower R-value. At a later stage, I will cover the insulation with a thin plywood.
With the Medium High Roof of my Ford Transit and my 5′-7” height, I have barely an inch left, to walk up straight inside the van. With a High Roof van or when you’re smaller than me, I would advice to add another layer of Poly-Iso along the entire length of the van, covering all the ceiling cross-members and thus avoiding any heat transfer from the metal of the cross-members.