Need help with installing laundry sink plumbing

[cliffalb]

Hello everyone, I'm trying to install a sink in our laundry room. So far I was told by an "expert" @ Lowes that I don't need a separate vent for the sink. I attached a photo of the current plumbing. I want to add the sink 16" to the right of the 3"main drainage. Looks like a 1 1/2" vent pipe is intalled next to the washer drain before going to the main drain. Can I use a double san like the pic I attached 3" main with 2" sides? Any advise would be appreciated.

 

[Smooky]

My guess is there are other things draining into the three inch pipe from above. If that is the case you can not use it as a vent. You might have to do some more exploring.

 

[Sponsor]

 

[Standardairconditioner]

My guess is there are other things draining into the three inch pipe from above. If that is the case you can not use it as a vent. You might have to do some more exploring.

Why not? That's probably the main vent stack going straight to the roof.

The homeowner will need to verify and provide more info.

 

[cliffalb]

If it is the being used as drainage from the second floor, what is the alternative? Since it's on the main floor and sharing a wall with the garage, can I just add a vent pipe that will go through the garage wall and out to the side of the house instead of the roof?

 

[Terry]

The sink will need it's own vent. It can be an AAV in Washington.
Since the 3" is a waste stack from the floor above, it can't double as a vent in Washington.
Depending on the height you need for the sink, you may be able to cut in a single santee above the other one. If not, then the double santee.
You will be able to glue the bottom of the fitting, and either use a shielded coupling for plastic to plastic, or an ABS slip coupling and be very quick about it.
That only works if you have some movement of the pipe from above. If it's fairly solid, then the shielded coupling would be easier.

 

[cliffalb]

The sink will need it's own vent. It can be an AAV in Washington.
Since the 3" is a waste stack from the floor above, it can't double as a vent in Washington.
Depending on the height you need for the sink, you may be able to cut in a single santee above the other one. If not, then the double santee.
You will be able to glue the bottom of the fitting, and either use a shielded coupling for plastic to plastic, or an ABS slip coupling and be very quick about it. That only works if you have some movement of the pipe from above. If it's fairly solid, then the shielded coupling would be easier.

Thank you... I'll get an AAV...is it easy to install?

 

[Terry]

The AAV can go on the trap arm under the sink. Yes, very easy. They need to be accessible.

 

[cliffalb]

Thank you!!! Now just have to wait on the wife to decide which sink she wants so I can figure out the height for the drain.