I need to add a utility sink and the drain would connect directly into my main stack (see attached picture). Is it possible to add a connection to the main cast iron stack, without cutting out a section and adding a new fitting? Basically, I am suggesting cutting a hole in the side if the cast iron stack and adding a saddle Wye (see picture)my stack as it is now.

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    I don't see any picture?
    – Reid
    Commented May 28, 2015 at 3:35

2 Answers 2


My understanding is that saddle wyes are prohibited under most codes, but you should check with your local jurisdiction to be sure.

The usual way is to support the pipe top and bottom, cut out a section, and then put in the new wye with hubless rubber connectors.

  • Thanks for your help. That was the answer I expected, and after a little more research, it seems not that much more difficult to do it right, since both methods involve cutting into the cast iron stack. In the unlikely event I would totally screw-up, I would be able to get a professional plumber to save the day.
    – Free2bme
    Commented May 25, 2015 at 14:43

enter image description here

I've included a picture of the stack below. After more research, and the help given here, tt is my intention to remove enough of the the stack to insert a 3" PVC wye, using a two short pieces of PVC, glued to the wye, and using two Fernco no hub couplings.

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