OK for foam and PMF walls?

[kklowell]

Is this what I want to use to make the walls and roof of my "foamie" truck camper? https://www.homedepot.com/p/Owens-C...Rigid-Foam-Board-Insulation-88WDNGX/315197857

 

[bullfrog]

Most people use 2" for strength up to 4' runs or heights. 2" is much stronger than1 1/2". If you PMF using the sock principle and use extra reinforcement at the joints you may be okay as long as you don't try spans much over 2' without reinforcement in my opinion. It doesn't take much to reinforce as in a 3" piece of 1/4" plywood or 1" x 2" rafter embedded in the side walls. Tnttt.com has lots of examples and stickies.

 

[kklowell]

Thanks, Bullfrog. I'm perfectly willing to use 2", and plywood strip reinforcement should be quite easy. I'm going to have to Google the sock principle though.

 

[bullfrog]

It basically uses the idea of entirely enclosing the structure with PMF. There is some shrinkage as the PMF dries and causes the structure to become stronger. Sort of like a tension beam becomes stronger. There is a description on tnttt.com. You don't have to do it all at once but once you are done building the structure coating every surface with properly applied PMF makes it very much stronger while not adding much weight. I would suggest you make yourself a cooler just to see what it is like to work with the materials and test it yourself before starting a big project, at least do a few test panels to destroy.