For the sake of accuracy. Unless Showhauler has changed the constructiion since last May when was at the factory they are not using Styrofoam insulation in the floor.

They were using expanded polystyrene foam insulation "beadboard". This has a R value of R-4 per inch.

Styrofoam is the Dow Chemical Co brand of extruded polystyrene. It is R-5 per inch. It is not the same thing as beadboard.

Most of the RV industry uses beadboard even though many companies incorrectly call it Styrofoam.