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Community and Q&A

LP WeatherLogic vs. Zip?

BrunoF | Posted in General Questions on

In my quest for an airtight structure I have considered taped OSB, Zip & CDX sheathing materials but recently someone here mentioned LP Weatherlogic as another option.  I am in zone 4A and will need my walls to dry in and out so don’t want vapor impermeable systems.

From what I can find on Zip’s website, the vapor transmission rate for the panel is somewhere between 1-3 perms.  LP states that their Weathelogic panels have a vapor perm of 5.35 perms as per ASTM E96 Method B.

It seems that the LP material is much more permeable but how much will that impact the wall performance in practical terms?


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  1. Expert Member
    Michael Maines | | #1

    I'm not sure about LP but the least permeable component in a Zip panel is the OSB itself; the coating is 13+ perms. I imagine the same is true for LP. There are exceptions but in most cases, everything else equal, for building performance, the more permeable the sheathing, the better.

  2. BrunoF | | #2

    Thanks! It looks like LP could be more than 2x as permeable than Zip in this case.

    1. Expert Member
      Akos | | #3

      I'm pretty sure that is the perm rating of the WRB coating. OSB perm ratings tend to be all over the place depending on the wood mix so I can't see them proving a spec for the complete panel. Nobody would show a perm rating on OSB with two decimal places.

      Overall, it looks pretty much the same as ZIP.

  3. BrunoF | | #4

    according to the data on page 5, the 5.35 rating is for the sheet of OSB, it looks like it may be an average of the results for the 7/16", 1/2" & 5/8" thick boards.

  4. Expert Member
    Michael Maines | | #5

    On next month's BS+Beer Show, July 6, we'll be talking with LP's manager of building science, Neil Freidberg, so this will be a good question for him.

    1. BrunoF | | #6

      is there a way to connect with him ahead of that date as I may be framing by then?


      1. Expert Member
        Michael Maines | | #7

        I don't have direct contact info for him, we're going through their PR person. But I have usually had good luck calling the technical help lines for questions like this; the engineers and scientists working for manufacturers often seems to enjoy discussing their products with the public.

  5. dirkgently | | #8

    Thank YOU so much for posting this question. I am not much of a computer guy and able to understand tables and such (smart work) but, attached is a doc I got from LP site. could opinions be had on this?
    Would 5 perms be vapor open enough to use in double stud wall with cellulose? If so that could be a game changer.

  6. xbcornwellco | | #9

    In the grand scheme of things, really depends on what you can get stocked. I had a nightmare of a time trying to get LP WeatherLogic, ZIP I can get all day long. I'd love to get LP though, main customer contact wasn't helpful locating stock.

    1. Mcshunatona | | #10

      What area of the country are you in? Builders First Source locations can usually get either product nationally.

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