Metal building condensation

..local car collector put his collection in a new metal quonset hut that he had built.A few days later he went out and every vehicle was soaked from the door handles down.He installed vents and a series of fans blowing along the walls progressively that solved his problem.
we used to install 6mil plastic on the inside of the 2 x 2's in our modest portable moose camp to create a dead air space as was already suggested.