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I live in an industrial loft. My downstairs neighbor is a factory. When they're running, fumes come up through my bathroom into my apartment. It's serious problem.

The guy who lived here before me put in the pipes himself (he left behind the tools, even) and I'm guessing he did a slapdash job of sealing around them. I'd like to find the penetration that the fumes are coming through, make an airtight seal around that pipe, and live in peace and harmony with my downstairs neighbor once more.

Problem step 1: How do I figure out which penetration is leaking fumes? (Some of the penetrations, like the 3 water lines to the faucet, are closed off behind a boxy sink, too.)

Problem step 2: How do I seal it?

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Just curious: in what jurisdiction is such a combination of residential and industrial usage, without air separation, even legal? – DJohnM Apr 28 '14 at 22:20
It's a "live-work" space, and the guy who lived here before me DIYed most of the plumbing and cabinetry, such as it exists. Much of it probably wouldn't pass code, on a proper inspection. But that's loft living for you. – baudot Apr 29 '14 at 2:36
up vote 2 down vote accepted

Solution step 1: Just seal all of the penetrations you can find. If that doesn't help, you'll probably have to start tearing off drywall to get at hidden pipes if you're sure the smell is seeping through gaps between plumbing and the floor.

Solution step 2: Use Spray-applied polyurethane foam. Dow Great Stuff works well. Just be sure to wear gloves!

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He should really be using a fire-stop caulk. Great Stuff has a fire-stop version available in the US only, but outside of the US you need to use a different product. – Steven Apr 28 '14 at 18:24
Thanks for the recommendations. I picked up a bottle of this and will be trying it tomorrow, first thing. – baudot Apr 29 '14 at 2:37
24 hours on, and this seems to have done the trick. I haven't smelled my downstairs neighbor since. Bonus points: Three of the penetrations were hidden behind the sink, on its cabinet stand. For those, the closest I could get to the actual wall penetration was the hole in cabinet below the sink. Liberal application of expanding foam for the win. – baudot Apr 30 '14 at 21:04

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