R-38 icynene in attic space

mjlbAugust 14, 2012

I would be surprised if someone has had this exact issue, but I'm hoping for some direction in researching this. (e.g. I've been to icynene.com, but didn't find answer that I wanted.)

The attic insulation is R-38 icynene. The inspector is suggesting that the icynene must be covered with gypsum board. I thought there might be a difference if the space was occupied vs unoccupied attic space? b-t-w, the attic space ceiling ht is much too low for future occupied use.


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Code requirement for an ignition barrier may be satisfied by 1.5" of mineral fiber, 3/8" drywall or 1/4" wood structural panels; other ignition barriers, including spray or roll-on fire barriers, may be accepted.

See link below for picture matching your situation. Your SPF installer should have mentioned this requirement.

Here is a link that might be useful: Decoding Thermal and Ignition Barrier Requirements

    Bookmark   August 14, 2012 at 6:32PM
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Ignition and thermal barriers are different, but related concepts. Having one doesn't preclude the necessity of having the other.

    Bookmark   August 14, 2012 at 6:42PM
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Wow, that was FAST, Worthy! From the date on the powerpoint booklet, I guess this is timely. The drawings at the back of the booklet are very helpful (our situation is a vented attic). When I've had a chance to discuss with builder and inspector, I may be back on-forum.

Thanks so much for your help!

    Bookmark   August 14, 2012 at 7:31PM
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Hi mjlb,
We'd like to understand more about your attic insulation and the gypsum board suggestion. You are welcome to contact our Building Science team to discuss your unique situation and get to a solution, please call us on 1-800-758-7325 (tollfree). Look forward to hearing from you!

    Bookmark   August 16, 2012 at 3:53PM
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additional info.


open or closed cell? you are aware that to achieve
R-38 will take several inches of foam?
open cell is about R-4 per inch closed cell about R-7.
code doesn't accept q or k values invented by foam

best of luck.

    Bookmark   August 16, 2012 at 6:16PM
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Thank you all! It never ceases to amaze me the info available on-line.

Geez - a forum devoted to thermal barrier and ignition barrier for sprayfoam - who'd a thunk-it?

I passed the icynene 800 tel number on to the builder, since he is more conversant with the details of this project.

    Bookmark   August 16, 2012 at 6:37PM
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