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R-38 icynene in attic space

Posted by mjlb (My Page) on
Tue, Aug 14, 12 at 16:56

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, 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.


Follow-Up Postings:

RE: R-38 icynene in attic space

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


Ignition and thermal barriers are different, but related concepts. Having one doesn't preclude the necessity of having the other.

RE: R-38 icynene in attic space

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!

RE: R-38 icynene in attic space

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!

RE: R-38 icynene in attic space

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.

RE: R-38 icynene in attic space

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.

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