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Discussion Starter · #1 ·
New to the forum and appreciate any help.
I am installing a full bath in my basement. As seen in pic I have a 4" cast iron vertical waste stack that goes to outside of house and also horizonal under slab along basement wall. I want bathroom to start a couple feet from stack and in this order from stack; Toilet, Sink and Shower. Where in this configuration do I put the Air Admittance Valve? Thanks so much for any advice.
 

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how far away is shower trap from sink.
also what is on the horizontal and vertical stack
 

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Discussion Starter · #3 ·
The cast iron stack is connected to a full bath on the next floor. The horizontal run from the stack under the slab in the basement is connected to a washer drain and floor drain only. The stack vents to a 3" pipe through the roof. Vent is hard to access and also I dont think it can handle the new full bath in basement.

Thanks!
 

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how far from sink is shower going to be?
 

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Discussion Starter · #5 ·
Toilet, sink and shower will be in line (next to each other) at just a little more than minimum code requirements.

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depends on code if you are worried about it. i would put aav under sink and let it be a wet vent for shower and the toilet is fine
 

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Discussion Starter · #7 ·
Jay,

I am curious why the aav would be at middle fixture as opposed to, say at one end of the branch? I don't do much plumbing so I just dont exactly understand why the sink? Is it because the trap for the sink is the highest trap in the branch?

Thanks for your help!
 

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it would be like running the vent straight up and arming over to catch a shower then continuing up to catch sink with a t then vent going up through roof . also sink is highest fixture . you could put one for shower and then another for sink. toilet is self siphoning so it well drain through vent stack
 
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