put my big boy pants on, a Neeeew camper build.. suggestions on insulation

[Itsavanman]

so my expedition popup toy hauler turned out pretty crappy.. on its maiden run, I wound up breaking my collarbone, the day were supposed to leave, it downpoured all day.. and the camper had to be put away wet.. and I couldn't do anything with it for 3 months. And yup, now that im healed, the canvas is a friggen science experment, mold, and MOSS!! lol. after I discovered this, I vowed to never own another popup.. farg that! so, I went and got a 12' vnose enclosed trailer to start with. anyways, its uninsulated. so need to insulate it before I do any camper stuff. so far the cheapest i can find is like $12 a piece 4x8 xps (expanded polystyrene) sheets. while not that expensive, I would like to see if theres anything else cheaper that would work as well or better than the foam. possibly cheaper I was thinking about using expanding foam and spreading it with a trowel. this camper is going to have ac and heat, and only get used spring to fall, so it doesn't need to be nuts.. but I would like it to not be an oven or freezer. so does anyone have any suggestions?

 

[IdaSHO]

XPS is the only foam I would suggest.

It is closed cell, maintains its thermal capacity, and is easy to work with.

 

[Huffy]

Look at rolls of foil faced insulation. It has a radiant barrier and a decent r value without taking up any space. I insulated a metal building with this and the results were exceptional.

 

[Roc8man]

Insulation

Best insulation per inch is polyurethane isocyanurate aka PIR or polyiso. Home Depot sells a brand called ThermaSheath R-Max 3. Comes with a foil face on both sides. It's pretty reasonable in price but probably more than XPS.

 

[IdaSHO]

"Best" is hardly the word I would use for Polyisocyanurate

Its heavier than XPS
Its thermal capacity diminishes considerably at low temps.
It also has a tendency to fall apart when used for vehicles (vibration)


I know lots of people use it, but I stick with XPS for the reasons listed above.