Adding a shower, do I need a vent ?

[Keith Kassen]

I'm adding a walk in shower to our master bathroom, and I have a question regarding venting. Since I am tying the shower drain in below the water closet do I need to add a separate vent to the shower drain? I'm concerned about syphoning from the shower trap.

The picture is the basement wall below the master bath, showing the existing 3" drain from the WC. Above that it transitions to 2" with a sanitary T for a lav and then vents out the roof.

Thanks for any help you can provide.

 

[Terry]

The shower needs a vent before it ties into the line below the toilet.
If the shower was above the toilet, it would have wet vented. Below though doesn't work.

 

[Sponsor]

 

[Keith Kassen]

Thanks for the fast reply.

 

[Reach4]

Your picture does not show the trap for the shower or your proposed location for the trap.

Your vent needs to be after the trap but before the pipe turns down (more than the 1/4 inch per foot slope for the trap arm) after the trap.

 

[Jadnashua]

Also, the vent line must be within a maximum of 60" of the trap when using 2" drainage pipe.

 

[Nicolette]

Yes, I would suggest getting a vent for your shower.

 

[Keith Kassen]

My original shower drain stack with vent is 10' away from the new location. Sounds like this is to far. I do have a vent stack that is within 60" but I would need to place a tee on it and some how tie it into the new shower drain. All of this work would need to be done in the joist bay since I do not have access to the walls above. Are there any other options I my be missing?

Thanks

 

[Jadnashua]

The drain and vent stack can easily be further away, but it's the actual proper installation and routing that is important. Before a drain can turn down after a p-trap, within the distance based on the ID of the pipe used (in the case of a 2" line, that's 60" in most plumbing codes), the vent must occur. That line must go up, at least 6" above the flood plane or often, 42" above the floor before it can go horizontal again to get it over to where the main vent line is. There's no restriction on the length of the drain line as long as it has the proper slope so that it can drain. On a drain, there is a limitation of the total angular change of direction before you are required to have a cleanout, though.