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Community and Q&A

Roof-to-Wall Flashing with Rigid Foam Board Insulation

budyjames77 | Posted in General Questions on

I am re-roofing my house (I live in Michigan in climate zone 5 by the way) and need some advice on how to properly flash and insulate where my roof meets my dormer. I also plan on re-siding my house someday. My question is how do I properly flash where the roof meets the wall of the dormer if I plan on putting up 2″ rigid foam boards (Johns Manville foil faced polyiso) under the siding of the dormer? I will be putting up new 5/8 plywood sheathing, then the rigid foam boards, then housewrap (housewrap manufacturer says to put their product on as the last layer before siding), then siding. Where does the ice and water shield and step flashing from the roof go onto the dormer wall? I would think I would run the ice and water shield from the roof up onto the dormer wall after the plywood sheathing but before the rigid foam. Am I right? I am totally confused on the step flashing though. No where seems “right” to me on where to place the step flashing.

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Budy.

    There are a few ways to handle step flashing against walls with rigid foam. I think you'll find this article helpful: Sidewall Flashing Options.

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