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Wall vapor barrier for new construction in zone 3A

Toby267 | Posted in General Questions on

Hello all,

I’m getting ready to build a 28×40 garage/workshop in Hot Springs Village, AR, climate zone 3A. 

Walls will be traditional 2×4 framing with 7/16″ OSB sheathing.  Siding will be vinyl to match the house (required by the POA restrictions).

I plan to insulate the walls and ceiling, and also intend to heat/cool the workshop portion of the building with a mini split heat pump.

I plan an underslab vapor barrier ( monolithic slab on grade), but I am unsure about the vapor barrier in the walls.  

My questions  are, should I use a vapor barrier, or just a traditional permeable air barrier  (i.e. tyvek) on the walls?  Do I place the vapor barrier on the outside of the sheathing, and use unfaced fiberglass in the walls to allow it to dry to the indoor conditioned space?

Thank you for your help on this. 


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  1. user-2310254 | | #1

    Hi Toby,

    Check out this article: FWIW. It's good practice to tape the seams on the OSB. Tyvek on the walls (properly detailed) as the bulk-water layer is also a good idea. (On a previous house, I used Commercial D instead of the standard product to promote drainage. But that may have been overkill.)

    Paying attention to air sealing while installing the interior drywall is also a good idea.

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