Question on interior vapor barrier for walls and ceiling

[SALIV8]

If I decide to go with interior metal siding for my walls/ceiling and insulate behind this metal siding (blow in)do I still need a plastic vapor barrier between the insulation and the metal?

I don't think so but what do I know..lol

 

[p_mori7]

I would say 'Yes'.

The vapor barrier prevents the flow of air through the wall (even with insulation).

Unless your metal interior sheathing is 100% (or very close to 100%) impermeable once installed, you should install a poly vapor barrier.

 

[kbs2244]

If by "blow in" you mean something dry you are also going to need a moisture barrier between the insulation and the outside wall.

If you are talking about foam it will be it's own moisture barrier.