Foam Board and vapor barrier

[wishin4snow]

I have a 36x54 pole barn in PA. Eventually I would like to add insulation to the building. This is something I plan on doing myself. I have been trying to research what I can and like the idea of using 1.5" foam board between the girts and spray foam the gaps. I would later add more insulation to get a higher R-value. Not sure if this would be 2" foam board or batt rolls. Either way, my question is if I need a vapor barrier on the walls. From what I can gather, I don't because the foam board.

I would eventually like to add some sort of HVAC system to just keep a comfortable temperature. For example, 55 degrees in the winter.

Looking for suggestions.

 

[dcg9381]

Much of "how you insulate" is regional. To me, the issue with "R panel" is that it has offsets. Vapor barrier wouldn't address the steel that's offset from the vapor barrier as it's not "pressed in" by traditional insulation. Nor would it necessarily matter if the R-panel comes down below the level of the foundation. If there is moisture in there, it can drain down and doesn't contact your bat insulation. IE, your additional layers of insulation are protected from moisture by the foam. But this is for a "cooling" situation when the inside of the structure is cooler and moisture might condense on the "interior" side of the steel.

But you're really taking about a heating case (55 degrees in winter). Part of that is "how" you heat. Most of the "tightly insulated" structures that I know about up north have ERV or HRV solutions to control interior moisture during heating season.