Here are some pictures of the flashing that went under the trailer, the insulation that went inside the floor and the sheathing (plywood) that went over the top.
First I put aluminum roll flashing under the bottom of the trailer deck. I used 2 rolls of 16×50 inch roof valley flashing.
After that I put R-Max insulation. Since the tube steel cross members are 2×2, I used 2 layers of 3/4 inch and one layer of 1/2 inch to make up the two inch total. I also used expansion foam to make an air tight seal around the edges.
Finally, we covered the top of the floor with 3/4 inch plywood.
Whew! I’m so glad to have the foundation finished!