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Community and Q&A

Flat Roof Insulation Help

Daniel Weaver| Posted inEnergy Efficiency and Durabilityon

Hi,

I’ve read a previous thread which addressed flat roof and insulation (venting versus non venting, etc). Seems like unvented is the way to go. That being said, I have a client who is remodeling a portion of her house who is very wary of her potential allergic reaction to spray foam insulation – she had a reaction years ago to a spray foam product. Rather than risk it again, even if I could convince her otherwise, what are recommendations for insulation options within an unvented assembly (as opposed to rigid foam above he sheathing) – blown in cellulose the entire depth of the cavity, wet or dry – rigid foam. others?

We will be rebuilding the entire roof assembly but are limited by zoning code to have the luxury of adding height by adding rigid insulation to the roof ( a question of inches). Waterproofing membrane on roof will be single ply membrane (EPDM). I presume this is a bullet proof air barrier.

Thanks for your help!

Daniel

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Replies

  1. Daniel Weaver||#1

    Apparently I need spelling help - typo in the title, should read Insulation!

  2. Expert Member
    Armando Cobo||#2

    Daniel, it would help if you describe your roof assembly for truss, TJI or dimension lumber, and height. Any ducts, plumbing or electrical? Where are you located, or what’s your climate zone?
    EPDM is your moisture and air barrier. Make sure your roof framing has good moisture management detailing, with at least 0.25/12 pitch for dry climate or 0.5/12 for humid climate; crickets, and long spouts or canales. Roof drains w/o insulation on top of the sheathing are difficult to fit and leak-proof.

  3. Daniel Weaver||#3

    Thanks Armando,

    We're using TJI's with a few low profile recessed, insulated cans in flat roof profile. I understand the drainage issues - looking for assistance on insulation possibilities.

    Thanks, Daniel

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