With little exception, my first portable house was built by using the most standard methods of construction. Like any other mobile home, my structure sit on a steel chassis — in this case, a 7’ x 14’ flatbed, utility trailer. I took most of the wooden deck off to save weight and put aluminum flashing over the gaps to safeguard against mice. The floor framing was laid on top of that. I used two-by-fours spaced about 24 inches apart on center.
Once that framing was assembled, I filled the cavities between the boards with foam board insulation and spray foam and capped the whole thing off with some %-inch plywood subflooring.
The walls were framed right over the wheel wells using headers just as you would over any other opening. I used two-by-four studs and rafters spaced twenty-four inches on center rather than the more typical sixteen inches. This is a fairly standard practice used to save both money and natural resources. At this point, I was using it primarily to save weight. My flatbed was rated to hold 7,000 pounds.
