[Greenbuilding] [BULK] Re: vapor retarder/barrier?

[Lawrence Lile]

>Our Inspector says the Oregon energy code says we must have a vapor
retarder on the inside exterior walls.  So,  your collective advice is
to use kraft faced batts rather than the poly sheeting,  with no vapor
retarder on the vented attic ceiling...is that correct?

Yes - a vapor retarder is much different than a vapor barrier.  A vapor
retarder impedes vapor transmission, plastic sheeting allows virtually
no vapor transmission.  Kraft faced batts are not a bad choice if you
have to have a vapor retarder.  I'd still consider cellulose, especially
if you are going to DIY. 

There should be no reason for vapor retarder in the attic especially if
it is vented.  

>What about the bathroom interior walls & ceiling...the code does not
address that?

Bathrooms should use water-resistant sheetrock, or even tile backer
board, where moisture can actually splash on the walls.  You definitely
want this to dry out, so no vapor retarder should be used.  Ventilation
should take care of removing moisture in the air.  

--Lawrence Lile