[opendoor]

Originally Posted by Shin Pad

One other thing - polyethylene is neither an air barrier nor a vapour barrier, it is a vapour re-trader.
https://www.finehomebuilding.com/200...apor-######ers

Sure it's a vapor barrier. Anything under 0.1 perms (6 mil poly is 0.06 perms) is Class I which is considered an impermeable vapor barrier.