GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Why not skip the sheathing?

jonedd | Posted in General Questions on

I am just a layperson who wants to build a pretty good home and have been considering two wall types, but as I’m reading, I feel like I’m missing something regarding the sheathing.

Many propose using exterior insulation to keep sheathing warm, but then some suggest that with diagonal wall bracing one doesn’t need any sheathing other than the foam (assuming either careful taping and/or membrane WRB and some other sort of air barrier). If so, what is the purpose of putting the insulation on the outside of the wall? I’m in central MN, so climate zone 6. If I go the rout of external insulation, I’d need about 5 inches (I want to use mineral wool to minimize foam) on the outside of a 2×6 wall which seems kind of tricky as far as screwing and siding alignment goes.

If I go with a double wall, the same basic question arises—if I use let-in bracing and membrane barriers to forgo rigid sheathing, isn’t that basically the same wall as above with just added framing to support the siding? This wall seems to make a lot of sense to me —
I continue to read about those who want to use fiberboard, densglass etc… and wonder if I’m missing another point of the sheathing.

Thanks for any reply.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Dana Dorsett | | #1

    Structural sheathing can also be turned into a very robust air-barrier, more rugged than taped-up foam or rolls of sheet goods.

    Many PassiveHouse designs also make good use the low vapor retardency of OSB, placing it at the optimal depth within the total insulation to control both air and moisture migration between the parts set up to dry toward the exterior vs. what dries toward the interior. This is something to think about when using very high-permeance exterior insulation like rock wool, in a house that may need active cooling on summer days when outdoor dew points are north of 70F. (That's less of an issue in central MN than it is in central MD.)

  2. GBA Editor
    Martin Holladay | | #2

    As long as your engineer and local building inspector approve of your wall bracing plan, it's certainly possible to omit exterior sheathing and instead simply install housewrap or a European membrane on the outside of your studs. I'm not recommending it -- but many people have done it.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |