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Community and Q&A

Spray foam: manufacturer vs. codes

dwilliams123 | Posted in General Questions on

So I have a closed-cell two-part spray foam I was considering using in a small, hard-to-access part of my attic, about 160 SF. The mfr says the foam is NFPA-286 compliant, with flame spread 25 or less, and approves it for use without thermal barrier at heights up to 6 inches, depths of 2 inches, and no horizontal restriction.

Now normally, spray foam in this part of the attic would require an ignition barrier, I believe. Yet the mfr says it’s not necessary, from my reading, unless I’m off base. So two questions:

Would it make sense to use an ignition barrier anyway, which is more work/money, or is it overkill? I mean, it will still burn easily, right?

And also, how would anyone inspecting it down the road know it was an approved use?


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  1. Expert Member
    Peter Engle | | #1

    It is important to read the manufacturer's instructions very carefully. make sure that it it rated for exposed use specifically in attics, and specifically attics that are used for storage, if yours is one of these. Reading these specs can be very confusion. You can have several different grades of foam on one spec. You can have foam that is listed for one type of protection inside walls and other building cavities, a different type of protection in attics used only for access to equipment, and yet another one for storage attics. And then there are all the options for crawl spaces.

    If your foam is actually rated properly for exposed use in the area you will use it, then go right ahead. If you are just concerned and want to reduce the risk, adding a ignition barrier will reduce the risk of fire. A thermal barrier will reduce it further. There is never a prohibition on going above code.

  2. GBA Editor
    Martin Holladay | | #2

    Don't accept the oral promises of the manufacturer. Asks to see test reports from a third-part lab. Any reputable manufacturer will provide such reports. That's how you can document the claims to satisfy your building inspector.

  3. dwilliams123 | | #3

    Thanks for the replies. I guess I'll just cover it with plywood, though the only access is through a 14 inch by 30 inch hatch.

    The part I still don't understand though is how to ever really know what type of foam was used. There are so many. When you come across old foam, how do you know for sure what it is?

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