drain and venting questions about plumbing a sink in my garage

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worldzfree

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seattle, washington
hello,

i posted this over at another forum but someone at work suggested i should post it here too.

i am a complete newb when it comes to plumbing a new setup. replacing something existing i have done quite a few times. i would like to plumb a sink into my garage. it's a two story (plus garage) condo/townhome. i believe it was built in 1999. this is the bottom floor (the garage). there is no crawl space. the washer and dryer actually reside on the top floor. there are couple of different pcv pipes that are exposed. they are:

pipe a- i know this a grey water pipe as i can hear water rushing through it when the clothes washing machine is running through it cycle. this pipe is right next to where i park my car so putting a sink here is not an option.

IMG_0400.jpg


pipe b - i assume this is some type of water pipe but i do not know what it is. this would be the preferred pipe as the sink would be right there.

IMG_0399.jpg


my questions are:

what is pipe b and do you think i can use it?
if i use pipe a or pipe b do i have to run some type of vent for the sink?

i hope my questions make sense. i appreciate any type of insight.
 
My best guess is that the pipe in your second picture is a cleanout. The code I work under states that if you use a cleanout as a drain for a fixture, that you have to provide another, equal cleanout.

Functionally, adding a sanitary tee to the riser and then putting the same threaded fitting into the top of the tee would suffice, but whether or not an inspector would accept that is another question.

That still does not provide the sink that you would install with a vent, which in my mind is the biggest problem that you face.
 
Without a lot more intimate knowledge of your plumbing system, I wouldn't recommend one for this application. An AAV only allows air in, it does not allow excess pressure OUT. In this type of situation, I would be concerned of having pressure build up in the section that your sink would be tied into, and would cause you trouble with the trap on the sink.

Edit:

Just looked at the attached document. If that is applicable to your area, it seems as though an AAV would be code compliant in this application, as long as your townhome is 3 stories or less.

I still would recommend against it.
 
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