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Roof insulation and venting

BeachSand | Posted in General Questions on

I reside in Washington State (Seattle side) and live in a 1964 tongue and groove cathedral ceiling type home without an attic or roof insulation.  I am having the home re-roofed with composition shingles in the near future and want some type of insulation installed.  The roof is a very shallow pitch (2).  The many contractors I have interviewed recommend rigid foam board be installed on top of the existing plywood deck, then new plywood on top of that, rain shield coating then the shingles.  Only one of the contractors suggested roof and edge-line venting also be installed to prevent a “hot roof”.
My questions is this:  Which route should I go?  I am not experienced in this arena and need expert advice to avoid any down-the-road issues.  Thank you!

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Beach Sand.

    Insulating above the roof deck is a good strategy, but you wouldn't add exterior rigid foam and vent the roof. That doesn't make sense. To get an idea of the different options you could consider, check out this article: How to Build an Insulated Cathedral Ceiling.

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