I am currently building a tiny house on a trailer, and while I did purchase plans from someone, the plans have since proved questionable, so I would like a second opinion on the wall system I plan on using. I live in a cold climate, so please keep that in mind.

The frame is made of 2×4 steel studs. On top of the studs we are using as a sheathing a new material called ReWall, which is made of recycled milk jugs and similar waste products, and it replaces OSB sheathing as well as sheetrock. On top of the ReWall sheathing we intend to use Tyvek housewrap, followed by a layer of 3/4″ of rigid foam insulation. The plans I bought make no mention of wood strapping for over the foam, but I intend to use it as I don’t see how siding could be installed without it.

On top of the foam will be cedar siding. To fill the cavities between the studs we will use spray foam insulation.

I am new to building houses and I want to know if there are any red flags involved in this layering system? Please let me know if I am missing something or if there is something I really should be doing differently. Thanks!