Toilet Vent and Wall Size
- Thread starter rcspott
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Toilet vent min. Is 2" however you need a full size cleanout before you can reduce to 2" if this is a second floor application you could flat vent a toilet with 2". cleanouts are not required on second floors (residential). and no 3" will not fit in 2 x 4 wall unless its steel stud.
That is very much dependant upon which code is in use in your area.
In my area, 1/2 the diameter the drainage pipe served, minimum drain for a toilet is 3", so 1 1/2", with at least one 2" diameter vent for each sewer connection.
In my area, 1/2 the diameter the drainage pipe served, minimum drain for a toilet is 3", so 1 1/2", with at least one 2" diameter vent for each sewer connection.
HoffmannFamilyPlumbing
Plumbing Expert
Depends which code your state adheres to. The International Plumbing Code (IPC) is 1 1/2" but the Uniform Plumbing Code (UPC) is 2"
3" pipe WILL fit in a 2x4 wall but the fittings will not. And you can not run a flat vent below the flood rim of the fixture unless it is washed by a fixture.
John
John, the toilet being flushed is washing the vent. no?
If the vent runs horizontal below the toilet there is no way that the toilet could wash it. There may be a small amount of water that will enter the vent but that is the problem. If the line is not being washed the vent could become plugged from waste being left behind in the vent. If the vent was being washed from above like in the case of a lav being armed off the vent it would be fine. No vent can be run horizontally unless it is 6" above the floor rim of the fixture.
John
John
This is how I see it.
The top one is wrong unless there is a fixture draining into the 2" vent above the toilet. The second on is correct you have no horizontal vent lines.
John
John
Ive done a lot of messed up plumbing then :/
Wet venting into a flat vent doesnt seem right either. All I can say is conventional is the way to go.
The only way I would wet vent a toilet would be on a conventional set up. With a 3 x 1/2 san tee arming over for the lav then reducing after the santee to 2" and vtr.... plumbing and I have a love hate relationship.
There is no need to use 3" vent up to the lav as a 2" vent with a 1-1/2 arm is OK.
John
Do you under stand the reasoning behind not running a flat un-washed vent below the flood rim? What could also happen with that setup is if there was a stoppage in the main line it could plug the vent and there would be no way to clear it.
John
we could probly talk about this for days but I have been failed by doing the things you have explained which is why plumbing is retarded! Lol
johnjh2o said:
That makes sense but the vent would get a cleanout any to test vent system.
I've got the time, I'm retired. How long have you been doing plumbing? I to look back at some of the things I did when starting out that I'm not proud of. It's all part of the learning process. 
John
John
What if it was on the 2nd floor? And if it was a dry vent how would you know it was plugged?
John
johnjh2o said:I've got the time, I'm retired. How long have you been doing plumbing? I to look back at some of the things I did when starting out that I'm not proud of. It's all part of the learning process.
John
been plumbing for 7 years. Im just a youngin.
desertwater said:
I dont think you understand the difference between washed and unwashed. My illustrations of the flat vent and conventional are being washed. And I would never diminish pipe size before arming over for a lav.
