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I've created an access hole in my subfloor for a couple pipes and a few electrical wires to get down into the crawlspace. It's coming up through the floor behind a chase wall, but the space is super irregular. I need to fireblock and also keep out rodents.

Would fireblocking foam meet code? I see a lot of posts that foam's just not actually effective fireblocking. Nonetheless, I'm thinking maybe some hardware cloth and fireblocking foam would do that job.

Does anyone have thoughts or suggestions?

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Sarah
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As you write about in the question, there are expanding foam products designed for this. The most common I see at the home improvement stores is Great Stuff FireBlock. It is less about stopping the actual fire than not giving it a clear path to travel and acting like a chimney.

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As far as code, it seems that it could comply with code. There are also a variety of easily purchased fire rated caulks that would work here..

UnhandledExcepSean
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    Using a listed fire stop foam has been legal every place I have worked even in multi level buildings and that's when inspectors start getting picky. Just using something that won't burn to plug the hole may not be legal because it is not specifically listed for this use. – Ed Beal Oct 26 '18 at 13:48
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As others have said, it depends on your code. But if you're just looking to block a "chimney" effect long enough to get out of the house you could stuff the hole with rock wool insulation. It's like normal fiberglass insulation but it doesn't burn.

Eden
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