I just read this thread and want to add my question to the original. I am in East Texas. I plan on converting an old woodworking room into a studio. It is 30 years old and was done the same way; i.e., rough plywood sheathing directly over the studs. It is paneled in the cheapest rough particleboard the owner could find (looks like a pile or large wood ships and shreds were simply saturated with resin, then pressed into shape), but the paneling is in good shape and I don't really need to remove it. We though about just adding a vapor barrier, then covering the entire thing with a new layer of paneling or drywall. The questions are: If we add a vapor barrier, where does it go - on the outside of the building with a new layer of siding over that or on the inside with a new layer of paneling over that? And where would the insulation go? Dian

What kind of climate are you in? This is for over a crawl space? Do you need to air seal as well?

For construction details, see the link above and this one from Martin Holladay of Green Building Advisor. As noted by Holladay, there is evidence that vented crawls work OK in dry Western climates and the cool moist climate of the Pacific Northwest. I was assuming you're not located in those locales. Essentially, vents should be closed and sealed, the floor sealed in heavy plastic and sealed to walls insulated in moisture-proof insulation (not the ceiling of the crawl) and ideally an exhaust fan installed and a passive air grille installed between the living area and the crawl. Details will vary depending on the depth of the crawl. There are many specialist companies on the East Coast US, and especially the Southeast where crawls seem especially popular. I've personally come across crawls in New York, Ohio and southern Ontario, so I guess they're present just about everywhere.

The crawl space treatment we used for the Habitat houses I helped build consisted of thick(6 mil) plastic sheets glued together(special glue) and then glued to the foundation(again special glue for the concrete in our homes) and glued around intrusions(pipes/etc.). Now, the actual reason for that installation was part of the radon mitigating system built into the house. But, it would work for your situation. We did the install using volunteers with minimal training---basically how to overlap the sheets and glue. There should be videos on You Tube illustrating the process. Look up passive radon mitigating systems.