Michigan builder – polyiso question
user-7059762| Posted inGeneral Questionson
Hello, Would like to thank everyone for the wealth of information here. I’m wondering if anyone sees a problem with installing 1 1/2” polyiso board with paper backing outside of my Tyvek commercial D. I have a local wholesaler selling sheets for $12 each but the paper backing could be an issue? I will be adding furring strips and hanging Hardi siding over.
Thank you
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I've used paper faced polyiso for the outside walls of my house. I put the WRB on the outside though underneath the furring strips.
In typical use, these boards are are meant to be protected by roofing membrane, so the paper should not be exposed to water. The paper tends to shrink when wet bending the boards, I would avoid leaving it exposed.
That makes sense. It is a Firestone roofing product that says the backing is an “organic material with anti mold properties”.
Thanks for the help.
Hi user_XXX (be great to have a name for the GBA Q&A community to use) -
Have had the same experience with moisture content of paper affecting the board; if pinned by the furring strips you should be fine but agree, this changes the location of your WRB and hence the location of "marrying" your flashings to the WRB.
Peter