It all started with an almost impulse purchase of a 16ft, 7,000lbs-rated double-axle flatbed trailer (the kind you could carry a tractor on) off Craigslist. With only surface rust, working lights and brakes, the thing was a steal at $1,400. It was used and is made of a durable, recyclable material: steel. When Andrea and I started to think about the kinds of materials we would want to surround ourselves with, we decided to minimize the use of plastic, paints. Stick to real materials like wood, metal, glass.

The first step was to recondition the trailer for its use as our house foundation. I cut the side rails with a sawzall, then ground some of them down with an angle grinder with grinding wheel. After such modifications (and losing a couple of hundred lbs in the process, always a good thing), it was time to paint a protective layer. My reasoning was that although the trailer was perfectly roadworthy, we would get a head start on inevitable maintenance. After going over the whole trailer with a wire brush, I treated the rust with a water-based solution that transforms the iron oxide into an inert surface, ready for paint. I then selected an aluminium color oil paint, because it is easier to see rust

The base is a 2×6 box, complete with joist hangers. Each joist lines up with the transversal ribs on the trailer (~24″ OC). We are now looking for a good insulation material to fill the nearly 5 inch height of our sub-floor system. Considering some reclaimed polyiso rigid foam board, which is the best insulating material out there.

On the right, you can see the underside of the floor system, with aluminium flashing and 6 mil plastic as an insect, vapor, and radiant heat barrier.