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Zone 3 minimum wall assembly

Mike Beckham | Posted in General Questions on

New construction proposed 2×4 wall assembly.
Latex paint, 1/2″ Sheetrock, BIB fiberglass, OSB, Tyvek wb,1″ gap, stone or smart siding.
Doesn’t this just meet the minimum requirements in Zone 3?

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  1. D Dorsett | | #1

    Nope! Doesn't make code min for zone 3 per IRC 2015:

    It would make it if it were 2x6 though. Code min is 2x6/R20 or 2x4 / R13 + R5 continuous insulation.

  2. Mike Beckham | | #2

    Thanks, Dana!

  3. John Clark | | #3

    Just an fyi it depends on your state. My state (Georgia) follows 2012.

  4. D Dorsett | | #4

    Unless otherwise specified in the question, I always default to the most recent version, which is currently IRC 2015.

    If you're looking for IRC rev (if any) that applies to your state see:

  5. John Clark | | #5

    Wish I knew why Georgia won't move to 2012 IECC. I guess the GAHB is balking at the min r-value for walls which requires them to drop their customary wall mock up (16" oci 2x4 /OSB/Housewrap) for the more expensive 16"/24" oci 2x6 or 2x4 w/exterior insulation.


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