Hi all,

Sounds like a lot of good ideas here, and maybe a couple of bad ones?

One thing that should be looked at is the difference between how plywood without an attached foam panel (SIPs) and the two types of available foam panels would react to being used to enclose a conditioned space. If you choose plywood and attempt to attach foam panels or other types of insulation, you run a pretty high risk of condensation in the walls due to conditioned air meeting ambient air behind the siding. The same holds true with panels that are not sealed correctly at all the connections and penetrations (doors, windows etc.).

There is also the issue of EPS vs. urethane panel performance relative to vapor drive as a result of permeability. EPS panels are permeable (air will move through them slowly) and as such should be allowed to breath behind the siding. Urethane panels are not permeable so this subject is irrelevant.

We have had pretty good luck with using vertical lattice strips hammer stapled to the OSB @ 12" O.C. and horizontal 1x3 firring applied over them for the siding. We vent top and bottom and use Cobra roll-a-vent as Will suggests to keep yellow jackets fom moving in. You might want to staple a chunk to the back of the siding where knot holes are for the same reason.

Good luck with keeping your barn useful!

Rudy