Foundation is done!
First, we skinned the top of the trailer (belly of the foundation) with 20″ strips of aluminum flashing using construction adhesive. By overlapping each strip by 2″ we created an “escape route” for any water that may find its way into the house but yet sealed it enough so varmints won’t be able to get in. Also, the overlapping pattern is set to allow air to flow over the skin when the house is being towed.
The foundation structure is made of kiln-dried 2×4″ Doug Fir prime dimensional lumber. Not much to say about it other than, it’s the good stuff.
We chose to go with battens of formaldehyde free / vapor retardant Owens Corning fiberglass insulation. The combination of this with the air gap created by the raised floor should be more than sufficient.
Finally, we chose T&G Dryply Plywood for the subfloor. It has a water-repellant coating on the top. It’s not as heavy as ground contact (GC) ply, but it should add a slight bit of protection should any moisture find its way from a spilled glass of something down the road.