Rust on floor:

You have the factory rubber mat with the felt backing (3/4" thick).

That felt must go in a motorhome application as you accumulate too much moisture inside.


If you don't get rid of it and replace it with a non moisture absorbing material, that is going to be trouble long term.


I put down thick polyurethane, then installed pink fiberglass and the original rubber mat back, adding about 1/2" thichness of insulation.


Before you work on the inside, pressure wash the area in between the outer sheet metal and the inner body --- open the drain valves, there are at least 7 or so of them, from 1" round to smaller plugs, and flush like you are trying to rid everything.. huge amount of dirt accumulate there.

When you are done --- let it dry.. that area must be treated from the inside to deter rust.

You must close off all the holes, etc to the outer body before you add insulation... there must be a vapor barrier on all sides or the insulation will become water logged.