I am installing a shower drain in a 2 year old basement that was only plumbed for a 1/2 bath. I have broken up the cement in the area for the drain which is right next to a vent stack. There is a 3" pipe that runs to the stack. Can I tie my drain directly into this? See attached photo for clarification.

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Originally Posted by rblystone

I am installing a shower drain in a 2 year old basement that was only plumbed for a 1/2 bath. I have broken up the cement in the area for the drain which is right next to a vent stack. There is a 3" pipe that runs to the stack. Can I tie my drain directly into this? See attached photo for clarification.

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You may tie to the main ONLY if you run a vent on the shower. A much better way would be to connect the shower to the lavatory drain line and let it be wet-vented by it. You do plan on venting the lavatory don't you?
Regards, Tom

Thanks for the response Tom. I have attached 2 more pictures that show the layout of the bathroom in a little more detail. Based on your response in taping into the lav vent, I would have to break out a lot more cement out to get to the lav drain. Do you still think this is the best method for this bathroom layout? If I connect the shower drain to the lav drain, I do not need to vent the shower? Shouldn't the lav have already been vented in the rough in stage?

Thanks in advance,

Ryan

You have a tough choice either way. If you connect to the lavatory drain and the lavatory has its own vent then the shower will be wet-vented by it. If you connect to the main you will have to roll up a wye on a 45 degree angle downstream from the trap and take a vent off it and revent back into the existing lav vent. Unless the lav has a vent run up- through the roof you'll have to run a vent on it. Your choice, Tom

If I tie the shower drain to the lav drain, can I vent the lav with an AAV vent? Or do I need to go up through the roof?

If local codes permit, a AAV's acceptable. Good luck, Tom

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Originally Posted by rblystone

I am installing a shower drain in a 2 year old basement that was only plumbed for a 1/2 bath. I have broken up the cement in the area for the drain which is right next to a vent stack. There is a 3" pipe that runs to the stack. Can I tie my drain directly into this? See attached photo for clarification.

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If I wanted to install the shower drain to the 3" pipe as this user asked, how would you attach to the 3" pipe? Do you cut a section off and put a tee in place, and reduce down to 2"? You'd also need a p-trap right? If you wanted to then vent this (which is necessary from what I can tell), where would this branch from? This vent would then find it's wait and connect up with another vent, possible the vent for the lav? Does it matter how you couple that vent together?

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Originally Posted by mtnbkr

If I wanted to install the shower drain to the 3" pipe as this user asked, how would you attach to the 3" pipe? Do you cut a section off and put a tee in place, and reduce down to 2"? You'd also need a p-trap right? If you wanted to then vent this (which is necessary from what I can tell), where would this branch from? This vent would then find it's wait and connect up with another vent, possible the vent for the lav? Does it matter how you couple that vent together?

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If you connect to the main using a 3 X 2" wye or combo you will have to roll up a wye on a 45 degree angle downstream from the trap and take a vent off it and revent back into the existing lav vent. Unless the lav has a vent run up- through the roof you'll have to run a vent on it.
The shower will be connected through a "P" trap and raiser. It does not matter how you revent, just that you do. Good luck, tom