House Wrap vs Vapor Barrier

12 responses

  1. Jay G
    June 4, 2014

    Why is there no jack stud supporting the door header? Also looks like there is no header support on the narrow window on the right?

    • Tim Carter
      June 5, 2014

      You need to go to Janice's house and ask her. Perhaps THAT'S why the contractor is no longer on the job. Did you read between the lines of what she said?

  2. Dwayne Van Horn, AIA
    June 4, 2014

    The best terminology for the product needed in Maryland is a vapor permeable air barrier. As an Architect I don't go around soliciting products, but I like the newer systems that have dimples or "sprinkles" on them that create the drainage plane between the siding or stucco materials. This not a rain screen system because the gap is still so small that the water can still make contact with the wrap and the back of the siding material, but the water is not trapped and can flow out the bottom. Typically sidings such as cedars and cementitious sidings and even stucco have surfactants that if allowed to make full contact with the building wrap and get wet, can deteriorate the building wrap material making it easier for water to penetrate. Living in Maryland we have the "best" of both north and south climates…. yes, where humidity and freezing cold seem to find the sweet spot for reaching dew point inside the wall from both interior and exterior. When you want a drainage plane and vapor permeability, look for a product that does all of these. I like Benjamin Obdyke's HydroGap because it has the spacers or dimples that look like little "blue sprinkles" like you might put on your ice-cream. You can use spacing drainage plane materials such as "Cedar Breather" in combination with other vapor/ air barriers to get air space you need, but as always verify with the siding manufacture the use of another manufactures material behind their product, they may have issues that you are not aware of such as nailing that will void the warranty.
    Take a look at this link:

    Also if you want to learn about the Study that U. Mass did on certain house wraps and felt that warns about surfactants in cedar, soaps and oils deteriorating the wraps.
    Dwayne Van Horn, AIA

    • Tim Carter
      June 5, 2014

      Dwayne, I mention the newer products that create a drainage plane. Great improvement for second and third-generation weather barriers.

  3. Ken
    June 4, 2014

    It was extremely difficult to read this article with 3 boxes over the text (Facebook,Twitter box) your subscribe box and a search box. You may want to have your designer add an option that will allow the reader to remove them if not wanted...

    • Tim Carter
      June 5, 2014

      You may want to check the settings on your viewing device to make the screen wider. Those options you dislike are the PRIMARY things that generate REVENUE so you can get this information for FREE. Instead of thinking of yourself and your experience, try to think of OTHERS who are working for you at no cost. That would be radical, wouldn't it?

  4. James C Gibson
    June 5, 2014

    A great history lesson. I never thought about location for vapor barrier.
    It does sometimes freeze in Ga where is the cutoff?

  5. Blake Woodard
    June 8, 2014

    Tim -

    From your last paragraph, it sounds like you are advising Janice to install both house wrap and vapor barrier. If that is the case, do you put them both on the outside surface of the OSB? If so, which one goes on top of the other?

    I understand that one potential problem with house wrap and vapor barrier is that if you install them improperly, you will trap moisture in your walls, causing wood rot and attracting termites? Do you agree?

    • Tim Carter
      June 8, 2014

      Blake, you better go back and read it again. I tell her exactly what and WHO to contact for clarity.

  6. Linda
    May 25, 2016

    When remodeling a bathroom from the inside can you put housewrap on the interior of the exterior wall with the writing facing out? This is in a cold climate that also gets hot in the summer.

  7. Linda
    May 25, 2016

    Ps there is tarpaper outside between cedar siding and sheeting

  8. Jack
    October 15, 2016

    Instead of a lengthy infomercial about what water vapors & house wraps are, how about a short, brief recommendation?


    1: Warm Climates: Exterior house wraps
    2: Cold Climates: Exterior vapor barrier + house wraps
    3: Mixed Climates: Vapor barriers

    Please do not take these as actual recommendations, but please do try to follow a format similar to above for making it simpler for people to follow in the future.

    Feel free to add several pages detailing the ins & outs of water vapor, condensation, rot, mildew, etc. in the paragraphs that come after the recommendations.

    This would make things much simpler for people, without having to read through page after page of semi useful material & attempting to decipher what it what & for what reason.

    Just make things simple.

    Don't get me wrong, useful information is present.
    It's just a little complicated following the pages of data.


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