Distance of toilet from Stack

[jpokerwinski]

Hey folks. I planning on using 3" PVC pipe for my new toilet. However, the distance from the toilet is 8' not 6 as recommended for 3" pipe. My stack is 3". i fall right in the middle of a 4" and a 3". My question will 8' be ok with 1/4 slope ?

 

[Jamesplumbing06]

3” vent can serve 12’ of 3” horizontal. 1/8” slope on 3” and up . 1/4” slope on 2”and smaller. If your still cautious then add a tee close to toilet riser and install a studor vent. Many other ways. But my book says those flow rates. And it’s what I have done for 18 years. And I give stoppage warranty. Good luck

 

[Diehard]

3” vent can serve 12’ of 3” horizontal. 1/8” slope on 3” and up . 1/4” slope on 2”and smaller. If your still cautious then add a tee close to toilet riser and install a studor vent. Many other ways. But my book says those flow rates. And it’s what I have done for 18 years. And I give stoppage warranty. Good luck

Not according to the Massachusetts Plumbing Code.(unless they changed it since the copy I have.
Limit is 8' for a 3" trap arm to vent.(I believe Uniform code says 6')
1/8” slope on 4” and up .
1/4” slope on 3”and smaller.
Air Admittance Valves are not permitted, except with Special-permission from the Board. But they are permitted.

 

[Jamesplumbing06]

International plumbing code book is where I plumb from.

 

[frodo]

 

[Jamesplumbing06]

Thank ya Frodo. I was looking for that table too. But just proves. Check your local code.

 

[jpokerwinski]

3” vent can serve 12’ of 3” horizontal. 1/8” slope on 3” and up . 1/4” slope on 2”and smaller. If your still cautious then add a tee close to toilet riser and install a studor vent. Many other ways. But my book says those flow rates. And it’s what I have done for 18 years. And I give stoppage warranty. Good luck

i am looking for the distance between the toilet and the Soil stack not the vent.
here is a rough drawing ( sorry i used paint to do this.)

 

[jpokerwinski]

View attachment 18542

my question is NOT about the vent but the distance between the toilet and the soil stack. i have a vanity drain in there as well that has the vent connected to it.

 

[Jamesplumbing06]

Then you just extended your length from toilet to soilstack/ vent. The sink in your pic with a secondary vent above it. That’s your starting point for the distance to toilet. For venting. Your soil stack is a soilstack until it reaches the highest drain. Then above it. Starts calling it vent. But 12’ from where the sink drain with a vent above sink is your measuring point.

 

[jpokerwinski]

Then you just extended your length from toilet to soilstack/ vent. The sink in your pic with a secondary vent above it. That’s your starting point for the distance to toilet. For venting. Your soil stack is a soilstack until it reaches the highest drain. Then above it. Starts calling it vent. But 12’ from where the sink drain with a vent above sink is your measuring point.

to make sure i got this correct... from my sink vent to the 3 inch line where the toilet is , is about 3 feet, the distance from the toilet to that same point is about 4 feet. so my measured distance is 7 feet? ( 4 + 3). if so is this ok ? thanks for the help

 

[Jamesplumbing06]

Yes as soon as you tap that 3” toilet drain with 2” for sink that’s your vented drain beginning. So your good.

 

[Diehard]

Thank ya Frodo. I was looking for that table too. But just proves. Check your local code.

Exactly! Codes vary, that was my point.
It would be nice for people having questions to indicate what their location is.
Here's the Uniform Plumbing code version.


Of course the big difference is the allowable slope for a 3" pipe. An 1/8" would allow a much longer run before the vent gap in the pipe would close up. But one must know and/or remember that you can't exceed that slope too much without affecting the allowable length of run. Otherwise the vent gap in the pipe can get blocked.

As far as using the vanity drain as a wet vent, now you're looking at likely a 2" line at 1/4" slope in combination with a 3" pipe at 1/8" slope. I guess it's okay as far as wet vent limitations, depending of course on the, unknown, applicable code.

EDIT: For example, I vaguely remember something about wet vents being limited to vertical lines.

 

[Diehard]

Hey folks. I planning on using 3" PVC pipe for my new toilet. However, the distance from the toilet is 8' not 6 as recommended for 3" pipe. My stack is 3". i fall right in the middle of a 4" and a 3". My question will 8' be ok with 1/4 slope ?

IF your applicable Code does, in fact, require 1/4"/ft slope you would not meet the written requirement that the length not exceed 6 ft but you'd be okay functionally based on the fact that the 6 ft limit was chosen based on a factor of safety.
In other words, theoretically a 3" pipe can be sloped at 1/4" for a distance of up to 12 ft before the vent space within the top of the pipe gets blocked. So if you do run it at exactly 1/4" slope for 8 ft you would be okay. Maybe not meeting the code but okay functionally.

Here's a picture to give you an idea what I'm talking about.

 

[frodo]

my question is NOT about the vent but the distance between the toilet and the soil stack. i have a vanity drain in there as well that has the vent connected to it.

and that is exactly what i gave you, the 'dirty arm ' length

 

[frodo]

..

 

[frodo]

 

[jpokerwinski]

..View attachment 18549

I assumed the measurement is how you have it and not as 'the crow flies'

 

[frodo]

I assumed the measurement is how you have it and not as 'the crow flies'

yes, you have to measure ''the length along the center line of the pipe and fittings.''

from the weir of the trap to the vent opening

 

[Jamesplumbing06]

Applicable code for sure. I was always taught to identify a wet or dry vent. At the very bottom where it starts horizontal. Is there a fixture connected above? A wet vent basically a vent that drains a fixture after it goes vertical. If it goes horizontal off main sewage then vertical straight to atmosphere then it’s dry. ?? Been doing it like that and passing many tests. But then again most inspectors don’t even understand vents. I just tell my guys if you got a 90 standing vertical. Take it out and install a tee with a pipe connecting to main vent stack in attic. Tubs and showers confuse a couple. But we allowed to arm over off a vented horizontal drain here. With the table above as maximum to trap. We are allowed 2 studor vents on a house with no larger than 4” drain and no smaller than 3” main vent. Standard house basically. That gives u enough for a kitchen and island. Kitchens have to if there is a window above. Framing inspector won’t let us cut a hole thru the king stud and stiff legs.

 

[frodo]

if using air admittance valve then you have to measure developed length from fixture to the air admittance valve

this is going to add 4' to the measurement of the developed length