Need vapor barrer in pole barn?

[srs]

I sent a PM to you.

sixdogs, fyi, I replied to your PM. I'll get back to you ASAP.

 

[Dawgfan3]

I used closed cell spray foam on the inside of my metal wall pole barn. I added R-19 batts on top of that, with OSB interior walls. The spray foam works great as a vapor barrier. It also seals all the joints air tight.

 

[pat32rf]

Its the water vapour in the warm interior air that is going to condense when it hits the cold metal surfaces. You have to keep that moisture out of the batts or it will condense on the inside of the cold outer walls and soak your batts, corrode/rust your steel and rot any wood within the fiberglass. If your area is cold enough to get foggy days or frosty nights then you need a vapour barrier.
Google the fiberglass insulation companies such as Dow for details...Neither OSB, plywood, nor drywall will stop water vapour transferring thru to the fiberglass..You need 6mil plastic and sealed joints.