I have a truck with a large doka (9 seater crew) cabin. This is uninsulated at the moment. I am considering options for summer and winter insulation but do not want to sacrifice head space.
I insulated the cargo area with expanded cork sheets in the interior ceiling and it worked beautifully as a conductive insulator. I can't use the cork sheets in the ceiling of the cab however due to height constraints.
Since cork is weatherproof, could I achieve good summer and winter insulation if I glue the cork sheets to the roof of the cab? For the summer, the cork would not transmit much of the heat radiation from the sun to the interior. For the winter when running the diesel heater, I assume the heat would transfer through the steel roof but then not pass the cork sheets.
Another option is to put reflectix type radiant barrier in the ceiling of the cab for winter insulation in order to trap the heat produced by the diesel heater. Combined with cork on the outside it might be a good all season combination.
In any case, I would appreciate some thoughts on the exterior application of cork insulation in a vehicle as I haven't seen it done before. I would put a roof rack over the cork to catch any vegetation when offroading and also add a sheet of plywood on top of the cork to prevent damage since the material is a bit fragile.