Hi,
Just recently got the DIY trailer fever and started planning a squaredrop build.
Overall plan:
1. 5x8 Westbrook utility trailer
2. 5x8 base storage platform with drawers, about 12" high
3. 5x9 normal trailer design on top, about 48" high (extra foot from angled back, thinking of going a bit wider the better protect base drawers from water)
4. Requires roof rails (kayaks, bikes, etc.), so walls need to be able to support typical car roof rack limits
5. Planning to skin with PMF
I initially was attracted by the foam-only walls, but came to the conclusion that I need some wood given the larger size, roof support requirements and just basically making it easier to attach things to the walls.
My next idea was to frame it all in 2x3 lumber, and cover it all in say 1 inch foam so I keep the benefit having rot-proof. I later realized that having walls thicker than 2" would complicated installing pre-made doors and windows.
I did see that HD sells 0.75 inch XPS, and even 0.50, which I wasn't aware of, so I still think it's doable.
Has anyone built walls that have foam on the exterior (minimal wood under PMF), but still with a wood frame (easy to build, can support roof rack, plenty of attachment options), that isn't too thick (to attach pre-made doors and windows)?