Quick vent question (near main stack)

[EthylOH]

Hi,

I'm adding a new sink right next to my toilet, which is right above the main stack.

Do I need to add a vent for the sink? The waste line will only be 5 feet long from the stack, and about 3 feet vertical (2" drain pipe).

 

[Standardairconditioner]

A picture of the ceiling from underneath will be nice.

I wouldn't touch the main stack at all, rubber couplings are not fun to sandwich between verticals.

Cut off whatever is after the toilet, and re-do the toilet as you do the new lav. The new lav is very close to the main stack, it'll get plenty of vent.

I guess this will be an illegal DIY in MA without a permit?

 

[Sponsor]

 

[EthylOH]

Sorry for the confusion...

I've added some details below:

I'm not cutting into the main stack. I'll be using a rubber donut at the flange to transition from CI to PVC.

If I need to add a vent, it will be up through the wall behind the sink. I'll then tie into the shower and tub aux vent in the attic (it's on the other side of the bathroom).

I was just curious if I needed to vent the sink at all because the drain is so close to the main stack.

 

[Terry]

If I were doing that, the lav or sink would get a vent.

 

[EthylOH]

If I were doing that, the lav or sink would get a vent.

Then a vent it is!

 

[hj]

The "main stack" is a DRAIN, not a vent, so it CANNOT be used for venting. In addition, the way you have it drawn the sink will have an "S" trap if you do not vent it.

 

[EthylOH]

The "main stack" is a DRAIN, not a vent, so it CANNOT be used for venting. In addition, the way you have it drawn the sink will have an "S" trap if you do not vent it.

This is what I plan to do. Does it look okay? (I didn't draw in the shower and tub traps etc under the floor)