Question on vapor retarder on interior dividing wall
First off, thanks to the many that respond to questions posted by us less experienced folks! I have learned a great deal from this site so thank you.
I have a workshop that I am currently finishing the interior. Currently everything is insulated and I’m turning my attention to the vapor retarder. First off, I’m located near ABQ NM which I believe is climate zone 5B. Very dry most of the year with a monsoon season that can get pretty wet. Anyway, my workshop is 32×40 and I have a dividing wall running down the middle so effectively two 32×20 spaces. Ceiling/roof heights are different for each with one at 10′ and the other at 12′. Flat roof. I am heating/cooling each space independently and for most times, will only be conditioning one side at a time. It will most likely be conditioned intermittently when working in one side or the other and given this is a hobby shop only, will probably only be used in the evenings and weekends by myself.
So my question is this: On the interior dividing wall, I plan to use Membrain up high where the lower roof trusses intersect into the higher ceiling area (2 ft). That seems clear enough to me. What I’m not sure of is the wall that is common to both work spaces. Should I be putting membrain on both sides of the wall, just one side, or not at all? What throws me is the fact that there are times I’d be heating/cooling one side and leaving the other alone whereas there are other times, I’d be doing the same but in opposite rooms. I should mention I will be insulating the interior wall (for insulation as well as sound reduction) with Roxul. I should also mention that the finish on the walls will be drywall/latex paint on one side and pine T&G on the other.
Thank you very much for your time and advice.
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