Hi, I plan to install one inch thick styrene foam insulation between the birch panels and the roof and rear aluminum skin, this is the thickness of the dimensional framing on our trailer. I see that others are using 3/4 inch. Do you see any issues using stiff insulation like this? ie; roof sags resulting in interior birch panel sags? Or, do you think this is a good way to go? Thanks for any feedback!
I used 1 1/2" Tuff-R (isocyanurate with silver on both sides). Love it. My trailer's a '76, so there are no curves and it has 1 1/2", but it's easy to cut the stuff in segments to follow a curved roof. It's not heavy enough to deform anything if your frame is in good shape.