... Trailer & food trucks that have been built or remolded on this forum has metal exterior sheeting with foam insulation (blue board ? & water proof), plywood interior sheeting with either SS or FRP on the inside surface. The metal exterior siding & the interior panel form moisture/vapor barriers on bother sides of the wall.
Even in house construction there is a moisture barrier under the exterior siding (old days tar paper; now plastic sheeting). ... Since water vapor moves from warm to cold surface, there should be a vapor barrier on the inside of wall studs to prevent moisture from entering the wall. ... This barrier might be part of the interior wall sheeting, if not it should be added.
For restaurant/kitchen construction, the interior moisture/vapor barrier is to prevent water from entering the wall and make wash down/cleaning/sanitation easier & simpler. ... thus old kitchens has glazed tile walls.
post edited by edwmax - 2012/11/22 17:57:39