The floor cavity is six inches deep, so we're using regular fiberglass batt insulation for an estimarted R-19 . The walls of the house will only be 3 1/2" thick so we'll be using rigid foam insulation to get the same R-value. The sides of our trailer were extended by the manufacturer to widen it to 8 feet. This created some small areas along the side, Michael has closed these in with sheet steel to create waterproof bays. These will be insulated and will carry the water lines to the bathroom. That way if a line ever leaks, the water would not get into the main floor area and we could get in to repair it.
Closing it in...
The floor cavity is being covered by 5/8" plywood sheets, we'll sand and varnish these to create the finished floor. A narrow opening is left open for now next to the porch area, this is where water lines can cross the trailer.
Our architect/builder consulted with a structural engineer and they decided to strengthen the house's structure with "whale ribs". These are five U-shaped ribs welded from 1 1/2" x 3" steel box beam that will keep the structure from twisting on the road. Michael and his team have the "whale ribs" all welded into place, next the walls will be constructed in between the ribs.
Disclaimer: no whales were harmed in the making of this tiny house!