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EPS sheathing under Tyvek

user-6731271 | Posted in General Questions on

We are currently in the design phase of our home. We will be building our home in northern California climate zone 3. I would like to use 1″ of EPS foam as a thermal break from the 2×6 wall cavity. I seem to be running into conflicting information on where to place my weather barrier. I would like to place it on top of the EPS for ease of flashing the outtie windows. However I have run across a couple articles that advise against this approach. Unfortunately they do not give a reason as to why that is a bad idea. Would you advise for or against this approach and why?

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  1. GBA Editor
    Martin Holladay | | #1

    You can place the housewrap in either location. The essential facts are these:

    1. You have to know which layer is your water-resistive barrier (WRB).

    2. You have to integrate the flashing in your window rough openings with your WRB.

    As long as you follow those principles, either way can work.

    Here is a link to an article with more information on this topic: Where Does the Housewrap Go?

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