Plumbing Question - Bathroom Vent

[ddurrett896]

Adding a small bathroom in my garage with sink/toilet and before I close the wall, I want to have the water lines and vent ran.

Is/when is the branch vent below in yellow required? Thanks!

View media item 111156

 

[Pntyrmvr]

Yes.


“Talk is cheap. Whiskey costs money.”

 

[klassenl]

Drawing from my experience as the child of a plumber; venting is always required. I am not a child any longer so I can't quite any rules or theories. If you can't get up the wall with a proper vent you may be able to buy a vacuum breaker (cheater vent).

 

[Kaizen]

Agree if you can put it in. Easiest long term thing to do.


Sent from my iPhone using Tapatalk

 

[Bert_]

In that drawing it's always required. Otherwise the sink is an s trap and it will siphon.

 

[matt_i]

If you didn't you'll have gurgling in the sink when you flush the toilet. Worst case would be that enough water gets sucked out of the trap to break the water-seal and allow the organic vapors to rise into the room.

Either way you'll have to redo it like the diagram.

An air admittance valve could substitute but consider its a moving part vs the statuesque pipe that will last forever if undamaged.

 

[flat350]

Distance of fixtures is a factor too.

 

[rlitman]

In that drawing it's always required. Otherwise the sink is an s trap and it will siphon.

Sort of. The drawing shows the branch vent at the minimum height, because it needs to be well above the highest point of the sink. But it doesn't need to be placed exactly where it is. If branching through the wall is a problem, you could raise that connection into the attic.

Optionally, the alternative would be to use an Air Admittance Valve. That would prevent siphoning, but is not as ideal, and shouldn't be done in new construction.

 

[Bert_]

Sort of. The drawing shows the branch vent at the minimum height, because it needs to be well above the highest point of the sink. But it doesn't need to be placed exactly where it is. If branching through the wall is a problem, you could raise that connection into the attic.

Optionally, the alternative would be to use an Air Admittance Valve. That would prevent siphoning, but is not as ideal, and shouldn't be done in new construction.

Yes, I was just saying the vent to the sink needs to be there.

Going straight up to the attic is more common and it's usually easier.

 

[BD1]

A loop vent maybe an option. They are commonly used for island sinks.

https://joneakes.com/jons-fixit-database/1707-How-do-you-put-the-vent-pipe-in-an-island-sink


Sent from my iPhone using Tapatalk

 

[Jackfre]

Running that vent, which is required, up the same stud bay into the attic as suggested tying it in up in the attic. If you want it to work and be trouble free, run the vent as shown.
Flat 350 is also correct. The “vent arm” for 1.5” has to be within 6’ of the trap arm and the 2” vent can be 10’ from the fixture. Now, I haven’t consulted the UPC in a lot of years so if there is updated info on that...

 

[welder4956]

A vent is always required. It can be tied in to the toilet vent as shown in your figure, or it can be a seperate vent that goes straight up through the roof. Your figure is just an alternate to running a seperate vent.

 

[pstnbly]

In our area tying back into the stack must be done above the floodline of the highest fixture.

 

[nadogail]

IMHO, your local authority having jurisdiction is the place to get the "Staight Scoop" for your area. In my city, the Building Department would demand an isometric drawing of your proposed drain, waste, and vent piping.

 

[dcg9381]

A vent is required. A branch vent when you have two more more things that require vents individually..

You could do one vent per instead of a branch.

There are "in wall" vent options - these come with a valve that allows air in but not out. They work, but have moving parts, and not sure when these are "legal" in terms of buildig code.

 

[firebirdparts]

To be honest, it's the 4" vent that's not required. FWIW. I don't mean leave it out, I just mean it can't actually do anything, not ever. The 1-1/2" vent is going to get the first crack at venting and it will.

You be the judge, though.