Based on recommendations from tiny home sites, workshops, and our local tiny house folk, I decided to use polystyrene foam board for the floor insulation. That was, until I did more research and learned about mineral wool, also known as rock or stone wool.
I went so far as to buy part of what I needed in the polystyrene, or XPS board, and brought it home to use. I even cut one piece and put it in to get a feel for it, but after researching some more, I found that mineral wool batts were a better way to go. It’s less expensive, greener, and easier to install. Not to mention it is fireproof and mildew and mold resistant. Mineral wool consists of long fine fibers,spun from molten natural rock bonded with a thermosetting resin. It’s semi rigid, which makes it easy to cut, and is sized to fit exactly in between standard spaced joists and studs.
Another bonus is that is adds soundproofing. Based on all of this, I returned the XPS board to the dealer and special ordered enough stone wool to insulate my floor. This sets me back about 2 weeks, but I feel it’s worth it for what I will gain.
I also plan to use stone wool for the wall insulation. Backed up against the Zip paneling, it should make a nice combination for an efficient wall system.