Sorry double post so I'm adding something witty here, well maybe not lol.

Yeah I'm a new poster but hey I've built panels and used them. I went a whole other route doing what in the small camper world was do sandwich construction/ala SIP for people that get so wrapped around titles and terminology. I have built 3 campers using this method and have had 2 go from Texas to east/west seaboard (1 each direction) and back and they held together bouncing and jousting down the road with no failures at all.

So for what I used, XPS from the box stores 3/4" thick within a simple pine 1x2 framing laid flat for walls and vertical for the roof (double foam in the roof due to 1.5" high vs 3/4" laid flat. Now here's the secret to all this and engineering is on my side. The strength isn't derived from the overall components but the amount of glue surface that is present and the sheer tensile strength of the glue. So with this simple structure which equates to a little over an inch thick after gluing the skins gives a strength of around 600 psi in a very thin format. I simply used 5mm luan skins with 3m 30DNF water based contact cement and it worked and I can walk on the roof of the campers with very little deflection at 200 lbs of lovable me. Water based glue so there's my green and look at the much less amount of materials needed to build such a strong structure.

Sometimes you gotta look around and think outside the box. I skinned the outer surface with FRP on the first (heavy hated it but its durable as heck) and aluminum on the other 2 same contact cement doing a vapor barrier and adhering to the luan.

I haven't built any in a while but will do another eventually but now I'm lining my sites on same type of construction in a tiny house build. If you wanna look at my campers do a search for microcampers.

Yes you can do this and not implode the world but before you do it test and do research on what products you choose to try out.

Structures also gain strength just from becoming closed boxes with all sides attached. I can't believe the pricing on these commercial panels, it's ridiculous and old traditional building codes and mindsets need to seriously change and move forward but the construction industry and its standards are more about making money and licensing than safety anymore jmho.

Yes this has been a vicious thread and I hope this might shed a little hope for it going forward.

To get an idea where the torsion and glue strengths scale look at a video on youtube for a person using just foam and putting weight on it and getting the failure point and then simply taking paper and gluing across both surfaces and testing again adds crazy strength from elmer's glue and paper.

Glue and foam usually don't jive and there aren't a lot of them that won't just melt it because they are petroleum based same as the foam is.
Steve

It looks like I will have to take that route of building my own panels as well I have been trying to get access to steel sip panels and always gets routed to middle man who doesn't offer any other value added services other than selling the panels to you from manufacturer. If I am shopping for tracks , fasteners and joists why would I need a middle man ? I am looking any manufacturer from whom I can buy the SIPs directly.