Insulating floor from underneath?

[pianobus]

Once again, feel free to direct me if you think this has been well covered somewhere-i have very limited access to internet so i can't spend hours searching threads first, but it seems like most people are insulating the floor above the metal and then adding another layer of plywood or something. I was wondering about spraying something in between the I-beams below the existing floor so as to maintain more height. Bad idea? is this going to trap moisture against the frame or something? Maybe i'll have to make some heat-shields for the muffler/pipes? Surely somebody must have tried this.

[Rusty]

Yes, has been done. Mine has sprayfoam underfloor from factory- is a Bookmobile. It is very nice and cozy. Protects underside from corrosion.

Consensus is that is possible, but difficult with hoses and wires under there. Fuel tank would need dropping.

Posts abound...