I'm putting a metal roof over a shingled roof.

I will run 1 x 4 pine screwed to rafters... then the metal will screw to 1 x 4.

My question :
Should I put a vapor barrier between the 1 x 4 pine and the metal ?
(visqueen or tar paper)

Vapor barriers are to be at the point where moisture condenses (due to cold), so that means on the inside of the attic rafters.

Thanks for the reply joypuly... but do not understand,

Or does that mean the answer is "no" no need for vapor barrier between metal and wood ?