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I have this vertical air exhaust pipe in my attic and I want to feed more things into it. What is the best way to attach more pipes to it? Can I cut a hole into the side with a hole saw, put in the same diameter pipe, and then seal around the edges? How is this generally done and what can I search to get me started?


  • That's ABS, not PVC. It requires a different solvent and there are likely code restrictions on connecting PVC to it. It's more likely a vent than exhaust. Commented Nov 30, 2019 at 22:35
  • Thanks for the clarification! Any thoughts on what it might be venting and how that differs from an exhaust for my purposes? Possibly something to do with Radon? Commented Dec 1, 2019 at 0:26
  • It is venting the sewer system. It allows air into the labyrinth of drain lines in your home that are draining tubs/showers sinks and toilets to the sewer system.
    – Kris
    Commented Dec 1, 2019 at 12:18
  • What things are you considering feeding into it?
    – Kris
    Commented Dec 1, 2019 at 12:23
  • just moist hot air Commented Dec 18, 2019 at 19:55

2 Answers 2


The ideal solution is to cut the pipe and insert a Tee. You'll have to lift the upper part of the pipe enough to slip in the T junction and then lower the pipe down into the T and glue it. Sabre saw works to cut pipe, but it makes the pipe wobble a lot, which is not a good idea, it could break the tee fitting shown in the picture.

I would rather secure the pipe to make sure it doesn't move, perhaps cut a length of wood to place between the pipe and the background, and then gently cut it with a hand saw. Less risk of damage this way. Make sure to be really careful when you cut the last bit of plastic, that's when the saw gets caught between the two halves and snags.

If that is not possible, I'd use this kind of fitting:

enter image description here

You get the idea. Drill into the existing pipe with a hole saw, then slap this fitting on it with enough glue to make it stick. I'm not really a fan of these though. They're supposed to work fine if properly applied, and they sure come in handy when there's no other choice, like when both ends of the pipe can't be moved...

Also check your code.

EDIT: It is called a "Saddle Tee" -- google that, there are several types so make sure you pick the correct one, especially wrt pipe material.


You would normally cut the pipe in half and install a tee similar to the one below in your picture and run your new pipe into it.

What exactly is this pipe for? If it's a drain vent or some type of heating exhaust, there are local codes that dictate what you can and can't do. Make sure you know what you're cutting into. Good luck

  • I'm not sure. It seems to be connected to several vents in the side of the house as well as running pipes down to the crawlspace. Possibly something to do with Radon? My dryer hose seems to run down into the crawl space as well. Commented Dec 1, 2019 at 0:25

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