SIP stands for structural insulated panel. Most are made from OSBs sandwiching a piece of styrofoam(polystyrene). Searching the Internet for something more lightweight than stick construction, we have found a panel made from steel and polyurethane based foam. These metal panels lock together using a proprietary tongue and groove seam creating a structural bond at each joint. We talked to many companies but after a lot of research we found the manufacturer nearby for CENTRIA panels.
These panels are the real deal. Well houses, Ice vending machines, refrigerated trucks. Watching storm stories on the weather channel, 2 dozen people survived a tornado in a gas station in Joplin because they hid out in the beer cave made from metal SIPs. They hold up in any weather for decades. R&D testing involves shooting 2x4s at hurricane speeds. The result is toothpick sized shrapnel and minor cosmetic damage to the structure.
If the eventual destination for the house is CO, the R-33 insulation value (equivalent to 18 inches of normal construction) will keep me toasty all winter. They are more lightweight which is a bonus for the construction crew 😉as well as the towing vehicle.