For My Tiny Wine Wagon, due to a major miscommunication regarding the ceiling joists, I ended up with non-vented 2x4's. Certainly this is not ideal but because the roof pitch is 12/2 or steeper, at least it isn't a safety issue.
However, this means I really only have one insulation option that will provide adequate R value while also minimizing (and hopefully eliminating) moisture issues; rigid foam.
In a nutshell, I am using 2" thick (6.5 R value) and 1-1/2" thick (4.5 R value) pieces to fill the 3-1/2" deep spaces between the joists. As such, fiberglass insulation would have been R13 and the rigid insulation is only R11. But, since we also do not have any venting in the ceiling cavities we'll need an insulation that will fully eliminate air circulation or warm air accumulation.
Next I needed to figure out how to install it.
The process isn't too tough, but worthy of a few quick pics so here goes....
Step One: Measure the space between the ceilings joists. Do not assume that the space is always the same.
Step 6: Admire, vacuum, and get ready for ceiling panel installation!