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Air sealing

ceeopa | Posted in Green Building Techniques on

Building a new house in zone 6 will use an edpm gasket seal on sill plate what is a general good product to seal remainder of frame prior to install zip sheathing. Not really thinking about windows as they will get their own treatment.  Just frame in general both externally and internally to aid in air sealing.

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  1. maine_tyler | | #1

    Some more detail may help. Most people tape Zip sheathing with Zip tape.

    A gasket, goopy substance, or tape connecting the bottom course of sheathing to the concrete or sill plate will be a good idea.

    Key to air barriers is continuity—corners, penetrations, walls, roofs, etc.—those all may require slightly different 'treatments' or products.

    Give this article a try, and if you have more specific questions, fire away:

  2. GBA Editor
    Brian Pontolilo | | #2

    Hi Chuck,

    What do you mean seal the frame?

    When using ZIP, the sheathing (with taped seams and caulk where needed) is the primary air barrier. The sheathing can be sealed to the foundation in a few different ways (again, typically, tape or fluid applied sealant). As you noted, windows and doors will be air sealed as part of their install process. And you'll need some way to transition the air barrier from the top plate to the ceiling, unless you plan to air seal the roof line instead. You can air seal within wall cavities with caulks, canned spray foam, etc. And you can install airtight drywall for an interior air barrier.

    But I'm just throwing out a bunch of stuff you may already know. If you provide some more info about your build or clarify your question with specifics, we may be able to be more helpful.

    1. ceeopa | | #3

      Thanks for the reply; to narrow my question, it seems there is a negative view of silicon chalk as air seal due to drying and potential cracking. Will use a suitable tape or liquid flash around sill plate, and or top plate area, as well as sheathing transition to footer., but thought since time (self build) is not an issue, i would detail the interior frame members as well i.e, such as where seams to studs join, top and bottom plate to belt and suspender air seal as zip system will be the external air seal. . Looking for a product to use in this approach to air sealing. In general I want to really work at getting low blower door test out the box. Is there a better method to insure a good air seal for instance at the drywall to ceiling area or will good muddying / paint do this function.

  3. maine_tyler | | #4

    Chuck, If you're talking about adding sealant between the zip sheathing and the studs—in addition to zip tape at the seams— I'm not sure that is a worthwhile 'belt and suspenders' activity. If you do want to do that, however, I do believe people avoid silicon in favor of something like an acoustical sealant, or some other high performance exterior grade 'sealant'.

    If you're talking about a redundant air barrier interior to the studs (which it sounds like that's what you're talking about) you may find this article interesting:

    If you're going through with an interior air barrier, some folks use a sheet product like ProClima products Intello or DB+, or Certainteed's Membrane. These usually involve tape for ensuring continuity at seams and transitions.

    Alternatively, there is the air-tight drywall approach. In this case, some people use epdm gaskets at drywall seems, and/or polyurethane sealant. See:

    Be sure to consider how all your barrier planes integrate, i.e. how will your exterior wall air barrier join with your ceiling air barrier:

  4. George_7224612 | | #5

    If you're doing a self build, you'll find this guy's blog fascinating. In particular, check out this entry:
    He talks about exactly what you're asking about.

    1. ceeopa | | #6

      Hey thanks! The article gave several plugs for possible sealants.

    2. maine_tyler | | #7

      I admire the quality of the workmanship there, and can attest to Contega HF being a quality product, but I don't understand the rationale for that sealant intensive approach.

      I didn't read every word in that post... what am I missing with the knee wall design there? Why didn't the sheathing seems just get taped? It's not just that all that Contega work seems finicky and pricey, its that it seems finicky and pricey for no likely upgrade in performance. Maybe someone that followed his blogs knows what's going on there.

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