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Community and Q&A

Zip R6 retrofit

davisgk | Posted in Energy Efficiency and Durability on

I am planning to replace the vinyl siding and windows on the second story of my 1963 colonial tract-home in climate zone 4 (Hampton Roads, VA).  The first floor is brick veneer. The second floor is currently sheathed in 1/2″ fiberboard.  I would like to add external foam sheathing during the re-siding process. There is plenty of info on wrapping existing sheathing with foam boards, but I am wondering about wrapping (or replacing) the existing sheathing with Zip System R6. It seems to me that this would simplify window and siding installation as well as drainage plane details. The walls are 2 x 4 and will be filled with R15 batts. Thanks for your experiences and advice.

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  1. Expert Member
    Peter Yost | | #1

    Hi Giles -

    No reason why you can't do this but here is the one thing I can think of off the bat that you will need to figure out or check in with Huber's ZIP tech support:

    The 1/2-inch fiberboard is of uncertain structural contribution to the wall so it is likely that the ZIP R needs to be fastened directly to the framing and if you don't remove the fiberboard, you have now introduced longer fasteners and different stress across the fiberboard.


    1. davisgk | | #2

      Good thought, I also need to ask them about spray foam compatibility with their integral foam. I’ll be sure to post their reply.

  2. user-6184358 | | #3

    The shear wall aspect ratio needs to be verified if it fits your application look at the ESR-3373 - R-Sheathing on the Huber website.Look under bracing. - section 4.5 ... indicates a 48" minimum panel length is needed for WSP in the IRC ...

    1. davisgk | | #4

      Thanks, I should have mentioned that the existing diagonal bracing is provided by 1X lumber let into studs at the corners of wall plates.

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