Venting question - unused 3" stack?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JasonK712, Feb 23, 2014.

  1. JasonK712

    JasonK712 New Member

    Hi. I am a homeowner and in process of finishing my basement and have hired my own subcontractors. My home was built five years ago (in New Jersey) and has two floors plus the currently unfinished basement space. I have been going nuts trying to figure something out as I trying to figure out how to vent the bathroom plumbing. I realize I will need to talk to my current plumber, but I am a planner and I want to know in advance what I should expect and make sure he does not try to avoid something as I want things done to code, but part of the problem is with how things were done when house was first built and while maybe it was fine for code, it may have made things harder for me now. Fortunately, I have the blueprints from when my home was built and as I try to figure this out, there is something very odd I think with how the original plumber hooked up the various plumbing vents. I'll do my best to explain. When house was built, the builder properly added a 2" future vent line that was supposed to be "capped and tagged" in basement (and I can see where that was "supposed" to be). However, the original plumber seems to have taken the main 3" sewage discharge line (i.e. the one that exits the house to connect to city sewer) and connected a vent line to what should be my 2" "future vent". What really boggles my mind is that I then see a 3" pipe that comes through the basement slab and nothing in basement connected to it. I can go into my attic and see that same 3" pipe come up and then go out to the roof vent. Shouldn't the main 3" sewage line have been connected to that "unused" 3" vent? I just cannot figure out why that 3" pipe comes out of the basement floor slab. I was thinking radon? But there is no fan. There does not appear to be anything mentioned anywhere in my blueprints, including plumbing diagrams that mentions radon. Would it be okay for my current plumber to fix all this by venting the main 3" sewer line and connect to this 3" vent that goes up through to attic and out through the roof so that I can then have him properly tie in the new basement bathroom vent pipes to what was supposed to be the 2" future vent exactly for what it was meant for (i.e. my future basement bathroom)? If so, does that 3" pipe coming through slab matter and are there any special considerations I need to talk to him about and consider.

    I added two pics hoping that will help show what I am saying. One is showing the 3" pipe coming out of basement slab, which goes up to attic and out roof. The other shows some connections. On far left, you can see the 3" main sewer line. On top of that just to the right of the red pex pipe, you can see the 2" pipe, which then runs over a few feet to the right and connects to what should have been the future vent. in the same pic on the right side, you can see the 3" pipe that was coming up from basement slab. It does make a 90 bend that looks like it is existing house, but it is actually bending and then bends again to go straight up and through to attic.

    Attached Files:

  2. Reach4

    Reach4 Well-Known Member

    Radon vents can be passive, with a fan inserted later if that is inadequate.
  3. cacher_chick

    cacher_chick Test, Don't Guess!

    Land of Cheese
    There would be no function in a plumbing vent coming up out of the floor, or being installed below the fixtures on the floor above.
    Any drainage stack going through the floor should have a cleanout in it, so what is there is questionable.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona
    quote; he does not try to avoid something as I want things done to code,

    If he is "reputable" he will NOT do that, and if you have a building permit and inspections THAT will ensure it is done to code, NOT anything you do.

    quote; when house was first built and while maybe it was fine for code, it may have made things harder for me now

    When the house was constructed, I, or any other plumber would NOT have worried about how easy it would be for you in the future.

    There would be no purpose to "venting the main 3 inch line" with that 3", or any other, vent pipe. The plumber may have installed the future 2" vent line, but then whoever installed the Radon system decided it would make their life easier if they just used it for part of their installation. Radon vents are "feel good" items, because you have absolutely no idea if they are doing anything other than looking pretty. That poster appears to be addressing a Radon vent installation.
    Last edited: Feb 24, 2014
  5. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    A vent on a 3" line may be a vent for a toilet, or perhaps another fixture that was cut in.
  6. JasonK712

    JasonK712 New Member

    Thanks guys for the feedback and input. I spent quite a bit of time yesterday staring at blueprints, plumbing diagrams and I think I figured it all out. The future vent pipe is there and the previous plumber tied in a utility sink, which he should not have b/c the utility sink (located on floor directly above basement) already has its own vent line that goes straight up to attic (so it seems that is "double vented" if there is such a term). So, I talked to my plumber and we'll just undo that and connect my vent for basement bath to what the future vent, which is what it was there for to begin with. I also found the vent for the house's 3" main up in attack, so that was a relief for me. The 3" pipe coming out of slab still perplexes me b/c nowhere in the building plans was there anything about a radon pipe and certainly no fan attached, which I see from above can be added later. I would have thought if something was being done for radon, it had to be marked specifically as such. In the house plans, the 3" pipe that goes up and out of attic was shown as a " 3 inch PVC chase", but I guess it does not matter. If I wanted to add a radon fan up in attic later on, I guess it makes life easier. Thanks guys.
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