vapor barrier

[roggabear]

Yes, I'm planning to pull the plastic down along the support beams. The attic space should be unheated. The question is whether I should continue with the plastic along the floor of the attic space towards the eaves or if I should stop the vapor barrier at the point where the support beams and the floor joist meet, see attached sketches, where the vapor barrier is drawn as a dashed line...

I don't have any vapor barrier in the exterior wall/roof on the floor below to connect to...

 

[meckis]

option B will be impossible to implement, right? I think the first option should be good enough. the warm humid air rises upwards. the roof is the most important!