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scott_matson
Installing drain vents

I am finishing off my basement and have started looking at some of my plumbing concerns. I know I need to install drain vents and somehow tie those drain vents into my main vent system. The upstairs plumbing fixtures are walled in so I cannot see any of the drainage pipes. My basement is stubbed in for a bathroom with toilet, sink, and shower. I see what I think might be a vent pipe, but there is not much pipe to work with if I were to tie into it.

So I have a couple questions:
1) Is there a way to tell what pipes are NOT actual waste water drains and which pipe is the one going to the vent? I can see the drains from the upstairs toilet, bathroom sink, and shower. There is another pipe angling up that I believe is a vent pipe, but I want to be sure before I go cutting into it

2) Do I have to tie into the existing vent pipes that lead out through my roof, or can I create a separate vent and just drill it out through the side of my house?

johnjh2o
Re: Installing drain vents

What is needed here is a picture of what you have in the basement.
As far as venting out the side of the building that is not allowed in most building codes. Any new vent line you run from the basement must either tie in above the flood rim of the fixture it is venting or exit through the roof.

John

scott_matson
Re: Installing drain vents

Image 1:

Image 1

Image 2:

Image 2

The pipe that I think is the vent disappears into the ceiling. It is most closely connected to the drain pipe for the bathtub. I can see these through the ceiling when I am standing in my basement. As you are looking at Image 1, the drain flows "down" the picture towards the main stack. Let me know if you need more clarification.

johnjh2o
Re: Installing drain vents

That does appear to be a vent but you can not tie into it in the basement. It must be tied in 6" above the flood rim of the highest fixture in the bath room , which would be the sink in most cases. That comes out to about 36" off the floor in the bathroom.

John

Fencepost
Re: Installing drain vents
johnjh2o wrote:

That does appear to be a vent but you can not tie into it in the basement. It must be tied in 6" above the flood rim of the highest fixture in the bath room , which would be the sink in most cases. That comes out to about 36" off the floor in the bathroom.

John

Reason being, if the drain from the upstairs bathtub plugs just downstream of the Y for the vent, IF you tied into that vent where you see it go through the ceiling, the wastewater could flow into the vent for the basement fixtures, with the possibility of plugging the vent or backflowing into those fixtures.

scott_matson
Re: Installing drain vents

I understand. Here is my understanding (or lackthereof) of what I need to do:

How is the basement plumbing usually vented? Is it tied into the upstairs vent system somehow?

What I am imagining is that I would run a vent pipe from my basement, up into my attic and tie that vent line into the main vent pipe. I then could use that vent pipe (which is now originating above every drain) and tie my basement drains into it. Does that make sense? Am I even close to what I need to do? Or do I have to run a completely separate vent up from my basement through the roof?

johnjh2o
Re: Installing drain vents

The new vent can tie into your existing vent in the attic. In your original post you said you had stub outs for a basement bath. Is there a vent pipe coming through the basement floor? If so this is the line that needs to be run to the attic.

John

scott_matson
Re: Installing drain vents

If my house has a VWD system already, with the upstairs drains tied into the system properly, do I even need to have the vent pipes extended into the basement? Several diagrams I've seen in magazines from Black and Decker and Plumbing for Dummies don't show the basement fixtures directly tied into the vent.

johnjh2o
Re: Installing drain vents

If there are no vents on the basement fixtures waste water from the upper floor fixtures would siphon the traps on the lower floor fixtures. This would allow sewer gas to enter the home. I can't imagine any book showing a system with out a vent on lower fixtures, you must be missing something.

John

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