I added a bathroom in my basement, chopped up the concrete, tied into the 4" main, and now when the tub upstairs empties.. water comes up out of my shower floor. What the heck didn't I do? Are vent the cause?

Hi Essexctyguy...

Sounds to me like you either tied into the tub drain for your shower vent or it could be as simple as a blocked drain pipe.

Snake the shower drain and see if the tub backs into the shower after that.

Let us know if you have any more questions... OK?

Mark

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