Insulating options for barn

[nightfury]

Is it an acceptable practice to place 2x4 flat between your timbers and spray foam and Sheetrock? I know normally you would sheath it, house wrap it and side it.

[DDW_OR]

a friend of mine did that with closed-cell spray foam to his pole barn in Minnesota.
he did not have to sheath it
during the winter he keeps the barn at 40 degrees.

now he as to deal with excessive humidity during the wetter months. High humidity = mold.