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Help Selecting WRB to Use Under Rain Screen.

cjwagner | Posted in General Questions on

I was all excited to use Huber Zip on a 1000 sqft unit I’m building but upon closer inspection of the plans I realized that the engineer spec’d the stronger plywood version that has higher sheer strength. However it seems to only come in 8ft lengths that won’t work for my structure.  I also think im going to have a hard time sourcing it here in California as no-one seems to use it. 

So I’m back to CDX. I was going to do Hardie plank siding over a rain screen but not sure what WRB to use in the application. I have used a lot of “Blueskin” but apparently it has horrendous problems with mold. I like the air sealing ability of Zip but don’t know if I can afford to use a self adhesive now. 

Can anyone suggest a good, middle of the road WRB to use under a rain screen? 

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  1. kbentley57 | | #1


    I would be interested to hear more about the blueskin failures if you've seen a common trend in certain installations. I can't offer much advice on the choice of WRB, but it's common to read that they're all pretty good so long as the installation is well done.

  2. Expert Member
    Akos | | #2

    You can't go wrong with taped sheathing and house wrap. You can still use the same Zip sheathing tape but over the seams of your CDX. Works great for sealing up the house.

    You don't need fully adhered WRB unless there is some very complicated wall/roof details.

  3. woobagoobaa | | #3

    “Blueskin” apparently has horrendous problems with mold?

    Do tell more please.

    Are you talking about VP100?

  4. Expert Member

    Blueskin is a brand name for a wide variety of products including WRBs and membranes. We should probably clarify which one we are talking about to avoid confusion.

    I agree with Akos' advice. Plywood, tape, and a regular WRB.

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