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What is the perfect wall (residential)?

user-6863985 | Posted in General Questions on

I just read in a blog that there is a description of  a “perfect wall” on this forum somewhere. I’d like to find it.

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  1. Aedi | | #1

    The "Perfect wall" is usually in reference to the concepts put forth by Joseph Lstiburek. You can find it here:

    It is more a set of principles than an actual assembly, though he provides some examples that meet some or all of his requirements in the article. The only building technique that has all control layers completely on the outside is PERSIST, which you can learn more about here:

    While PERSIST is nice, it is an expensive way to build, so it is not often utilized.

    1. burninate | | #2

      Relying entirely on exterior rigid foam continuous insulation is considerably more expensive than anything involving strict cavity insulation or double-stud & cellulose (and no way in hell do I think any of the several foams involved will last 500 years), but it's also a lot less complicated to actually construct if you buy the right fasteners.

      I'm trying to figure out the right way to do structurally resilient non-bridging double-stud wall panels in Sketchup. I've been trying on and off for six months. I am (irrationally?) convinced that there's some way to have my cake and eat it too, but I keep discovering new things about the sequencing or the detailing.

  2. GBA Editor
    Martin Holladay | | #3

    Aedi's answer is correct: the phrase "perfect wall" is used by Joseph Lstiburek to describe a wall system that others usually refer to as PERSIST.

    If you want general advice on high-R walls for a residential project, you might want to read this article: "How to Design a Wall."

  3. user-6863985 | | #4

    Thanks, I'll read the Lstiburek link. I'm doing a remodel, so it's the concepts I need to be sure I'm aware of.

  4. Peter Yost | | #5

    Just to be clear: the PERSIST wall is one fully-specified type of "Perfect" wall, with perfect meaning ALL thermal insulation on the exterior of the assembly, regardless of whether or not it is wood-framed, steel-framed, or masonry.


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