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The wall between my garage and the rest of my house (US) is the usual drywall-insulation-drywall wall framed out with 2x4 studs.

Can I run 1.5" PVC conduit through that wall perpendicularly (e.g., not a run inside the wall, but straight through) from a utility room into the garage, provided I fire-caulk around the conduit on both sides?

Edit-

What would change if I used EMT instead of PVC?

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That should be fine as long as it's Schedule 80 pipe (thanks, Ed Beal). A garage "firewall" isn't usually considered a fire-rated situation like you'd find in a multi-family dwelling. It's just a minor safety measure. Therefore, per my understanding, you wouldn't need a fire-rated penetration. You'd just need to seal it as you describe. Ask your local inspection office (even if you're not getting inspected) to be sure what they'd ask for.

Consider slipping a trim ring onto the pipe to cover the ugly red caulk if your garage is finished.

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    Being exposed it would need to be schedule 80 pvc.
    – Ed Beal
    Dec 8 '20 at 15:40
  • That's not really true. Some towns treat it as a true firewall - becoming normal near me and some requiring 3/4" drywall. Yes PITA but they are doing this because so many homes in my area have 3 walls against living space.
    – DMoore
    Dec 8 '20 at 15:44
  • If you can't run PVC conduit inside walls, isn't it all exposed and therefore always schedule 80? Is schedule 40 then only for outdoor runs?
    – Bort
    Dec 8 '20 at 17:10
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I agree with isherwood but I have dealt with cities that want an extended box (6") with a sealed opening. You are especially going to notice this in cities that require an inspection before selling the home.

So the answer is you need to call up your inspector and just ask them what they want. If the project is big enough they may ask you to pull a permit. I know I hate pulling permits for cosmetic stuff but when you poke holes in a firewall in garage for new plumbing for whatever the city will put 2 and 2 together and may make it a very long inspection... when they could just want some fire rated foam.

Note: that when you call the inspector and he says "Just do this". You can disclose this conversation to future inspectors and to potential buyers. Just having record of conversations like this have saved me days of work. New inspector comes out and whatever you did is grandfathered - instead of you doing whatever he wants.

To do this by strict firewall code I found a kit/brace that would meet standards. 3M makes it so I am sure it is available for schedule 80 and available in the US. Link to kit. (if someone finds US link add it)

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    I would dump a can of fire-rated foam into the wall around the conduit as well as the caulking. In the event of a fire it will swell and seal the opening. On the third hand, transitioning to metal conduit for a section that's through the wall would not be a terrible thing, and will hold up better in the event of a fire.
    – Ecnerwal
    Dec 8 '20 at 15:47
  • @Ecnerwal - that is a good idea. And if you have seen fire departments do their wall testing this piece of PVC would certainly be a flume. I know we are not talking about things that are in high likelihood but it is the reality of a firewall and really I have seen cities run the gambit. (My new home the city couldn't care less, where I just moved from they wanted to know why I painted my garage and what type of paint)
    – DMoore
    Dec 8 '20 at 15:50
  • @Ecnerwal - but what is funny is even using your setup, the city that wanted a 6" box... well I could have something that works 20x better but they want the 6" extension so they can check that box.
    – DMoore
    Dec 8 '20 at 15:52
  • @DMoore What is this 6" extension you speak of?
    – Bort
    Dec 8 '20 at 17:10
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    @schadjo - about 15 or 20 years ago a city asked me to box out 6" from wall and fill with fire rated spray foam for the PVC to enter. It wasn't a big deal but it was a bit goofy and random. That is why you should call your inspector. The collars in my answers look to be internationally approved so guessing that may look the best and make your inspectors happy. (if you don't want to call them I would install one of these collars)
    – DMoore
    Dec 8 '20 at 17:52

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