The white expanded polystyrene (EPS) foam stuff they use is hydroscopic (absorbs water) as does fiberglass batt type. Composite exterior walls with the EPS foam is typically on the side walls and front and rear cap have fiberglass batts in them (like in our TT). The problem with RVs is that there is no vapor barrier on the interior/warm side of walls and ceiling (like in a house) and moisture will migrate to the exterior skin and condense. This can be an issue if camping in cold weather and steps aren't taken to remove moisture laden air from the interior. If there is wood framing, moisture will lead to rot and for foam framing, it may corrode and there can be delamination of the exterior skin.
Is one superior to the other? Not sure. What I don't like about fiberglass is that they do a poor job of installing it correctly in walls and ceilings. It gets compressed in areas which reduces R-value and there's often voids with no insulation. We have the Reflectix stuff in our ceiling and when I looked into it a ways back, there was no solid evidence that it does much. The batt type insulation won't sag.
__________________
Gil & Deb & Dougal the Springer Spaniel
Langley, BC
|