Help with interpretation of the New Jersey plumbing code.

Discussion in 'Plumbing Code Questions' started by emanaresi, Jun 11, 2013.

  1. emanaresi

    emanaresi New Member

    Messages:
    4
    Location:
    New Jersey
    I am working on planning some plumbing for a timber framed home in NJ. I will be owner/builder and have done a good bit of plumbing but I am no expert on code. We have a couple desired fixture locations that create some venting issues and I am hoping you can help me to understand something in the NSP code book. My question is regarding 12.8.1 exception 3, what does it mean?
    All of the exterior walls will be foam cored sip panels that plumbing cannot run inside of. Further more, the entire exterior of the house will have large, exposed timber beams supporting the second floor structure. So, any fixture on an exterior wall is essentially impossible to vent from above without building an undesirable plumbing chase. Please see the bathroom drawing and the code excerpts below. I am sorry the drawing is not very good at this stage.. I am just working with general ideas at this point then I will refine the specifics.

    nj_plumbing_0303.jpg nj_plumbing_0304.jpg IMG_1691.jpg
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,156
    Location:
    Bothell, Washington
    In all my years of plumbing, I've never done it the other two ways.
    On the West Coast, they would laugh.

    Here, we expect every fixture to be vented above the trap arm, not below.
    I would be looking at fitting in a way to run vents, even if it's through cabinets. In many exposed structures, they still plumb to code, it's just that they go with it and find a way to make it look intentional.
    Last edited: Jun 11, 2013
  3. emanaresi

    emanaresi New Member

    Messages:
    4
    Location:
    New Jersey
    Terry, thanks, I understand that it would be "better" to directly vent the lav right off of the trap. However, would you say that I am in fact interpreting that exception correctly? I can run the p trap from the sink down into the floor, and over to a horizontal drain that is vented, as long as I follow the pipe sizes that are indicated? Is there any reason to believe that it would perform poorly?

    How would you recommend that I do it "correctly? The attached picture shows the frame and the exterior walls. The post in the middle of the wall is where the double lav sinks will be. As you can see, there is an 8x12 beam on the wall directly above. The timber floor joists will be exposed. There will be another 2x10 floor platform built above the ceiling to allow for duct work, electric, and plumbing for the second floor. Even if I built out a plumbing chase, it would have to be 10" deep in order to get around the beam. The only option I see is to move the fixtures around so that the lav can be on the opposite wall. That is, unless the above mentioned exception can work in my favor.

    IMG_1696.jpg
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,156
    Location:
    Bothell, Washington
    The one on the left I do, the two on the right I don't.
    I would rather use Studor or AAV venting than the two on the right.

    Have you shown your plumbing inspector those pictures and asked him?

    In forty years of plumbing, I've never looked at plumbing as something that could be left out if it was inconvenient to the homeowner. Sooner or later they would have called complaining about the smells, and then what?
    I do see that when I follow behind "handyman" plumbing. Then it's everybody's opinion about how to fix it. Not fun.

    Perhaps a plumber from New Jersey can step in here and explain if the drawings are correct for that state.

    Maybe so...........
    (3) Vents may be connected below the top weir of the fixture trap if the following conditions are met:
    a) The vertical section of the drain pipe shall be at least one pipe size larger than the trap inlet size.
    b) The horizontal pipe connected to the trap outlet shall be at least two pipe diameters long.
    c) The developed length of the trap arm shall not exceed the values in Table 12.8.1.

    I still would want to run it by someone there.

    Attached Files:

    Last edited: Jun 11, 2013
  5. emanaresi

    emanaresi New Member

    Messages:
    4
    Location:
    New Jersey
    Are the 2 right drawings sort of a form of combination waste/vent?
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,882
    Location:
    Cave Creek, Arizona
    exception #3

    NEITHER drawing for "exemption #3" would pass inspection in this area, or any other one I have ever been it. For all practical purposes the "vents" in the drawings are cosmetic and perform NO function as far as venting is concerned. Both of them show "S" traps and therefore the vents are useless.
  7. emanaresi

    emanaresi New Member

    Messages:
    4
    Location:
    New Jersey
    I guess it will be an aav then, under the sink.

    Would it be better to try to do a combo waste vent than an aav?

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