Vapor Barrier: MemBrain or Paint
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I’m getting ready to insulate the new workshop I built for myself – 44 ft x 30 ft with 12 ft tall ceiling. The slab is insulated with 2″ XPS under the entire slab, including the edges along with a 6 mil poly vapor barrier. The wall assembly is 2 x 6 studs, Tyvek, T1-11, Benjamin Moore latex primer, and Benjamin Moore Aura exterior paint.
The shop will be heated with a natural gas fired unit heater with a usual temp of 50 to 60 degrees in the winter, dropping down to 40 degrees when not in use for long periods of time (a week or more). There is a good possibility I may eventually add A/C at some point in the future. I live in SE Michigan, climate zone 5.
I will insulate the walls with 6″ of mineral wool and use the Air Tight Drywall method. My question is when it comes to a vapor barrier should I use a vapor barrier paint or MemBrain or nothing or ? Marty
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Replies
Use this when it comes to wall design and moisture. The temps of your use will mean that it is properly conservative (otherwise I'd use the Z6 values).
https://www.appliedbuildingtech.com/system/files/200311_abtg_rr_1701-01_moisture_control_guidelines_figure_update_final.pdf