The principle design goal for the flooring is to have a very rigid structure. I think the rigidity and strength will come from all the elements combined. So 2×8 floor joists attached to doubled-up rim joists and fastened to the steel c-channel And if we weld steel sheet to the bottom, this skin layer provides extra rigidity to the c-channel.
The trailer axle assembly could be welded to the c-channel forming a trailer but we are likely to go with a separate trailer and add 8×8 PT lumber “skids” below the flooring so the whole structure can rest on the ground or piers and raised and lowered onto a trailer when moving.
Here is a diagram of the flooring details. Going from top to bottom:
- SiP wall panel with exterior 2″ rigid foam insulation will give us R-
- This is attached to floor plate with screw/nails
- The wall sits on 3/4 plywood flooring
- The wall is also supported by doubled 2×8 rim joists below the flooring
- Floor joists are 12″ on centre with 7.5″ of rigid foam insulation in between
- There is a 1″ rigid foam insulation below the joists to serve as a thermal break
- 2×6 C-channel runs the whole perimeter and is bolted to floor rim joists
- A bottom plate of steel is welded to c-channel forming a rigid structure
- The c-channel could be filled with rigid foam insulation before exterior cladding is added
- Two skids made with 8×8 PT lumber are bolted to the bottom of the flooring and run the full length