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Is a single soil stack a requirement?

Soultrain | Posted in Construction Techniques on August 10, 2006 08:37am

Is it necessary to tie all DWV into a single stack?  I have 2 baths & a kitchen & none of them share a wall.

Is it required for a single 3 or 4″ stack going from roof to drain & everything ties in to it?  or could I tie each room into its own 3″ vent in the attic & then have them tie into the building drain in the basement?

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  1. Junkman001 | Aug 10, 2006 08:41pm | #1

    There's no reason you cant have more than one vent

    1. DanH | Aug 10, 2006 08:47pm | #2

      There are reasons for minimizing the number of vents: Fewer roof penetrations, less liklihood of a vent icing over, and probably one or two more. But no absolute restriction.Especially with plastic pipe, however, it's usually easy to tie them all together, assuming a moderate-size house with unfinished attic.

      If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

      1. JohnSprung | Aug 11, 2006 10:42pm | #3

        It generally looks better to have one well placed vent than a random peppering of the roof with little pipes.  The fewer the holes, the less the leaks, too. 

        IPC and UPC venting requirements are quite different, you have to check out which applies.  They're mostly stuff like total cross sectional area at least equal to the building drain size, vents at least half the size of the drain, minimum 1 1/4", increase one size for runs over 40 ft.....  

         

        -- J.S.

         

  2. hasbeen | Aug 11, 2006 10:56pm | #4

    My understanding is that you can have as many vents as you need and each one only has to be sized for the fixture is serves i.e a tub/shower would require a 2" vent. But maybe I'm all wrong. Ask your inspector.

    I don't understand the last sentence of your post. Maybe you'd get more response if you tried to restate it more clearly.

    Is that just Soultrain? Or is it Zion Train, too?

    +++++++++++++++++++++++++++++++++++++

    "Doubt is not a pleasant condition, but certainty is absurd." Voltaire



    Edited 8/11/2006 3:58 pm by hasbeen

    1. User avater
      Soultrain | Aug 11, 2006 11:07pm | #5

      I'll see if I can clarify.

      I don't really have a convenient way to tie all fixtures into a single stack without boring some very large holes in several floor joists.

      What I'd like to do is to run a seperate drain line for each fixture & tie them all into the building drain in the basement (4" pipe running at a quarter bubble).

      Also each fixture would have it's own vent line running to the attic & tie them together into a 3" line up there so there's only one hole in the roof.  However, there wouldn't be any continuous 3" line running from the attic to the basement.

      Sorry if I'm not conveying this very well...

      1. hasbeen | Aug 12, 2006 12:11am | #6

        Ok, that helps.No. I don't think you can do that. Reason? The toilets must have drains and stacks of the proper size (probably 3"). Thus, those drains and stacks must run both up and down in that size.I think you need to talk to your inspector, unless you don't have one.+++++++++++++++++++++++++++++++++++++"Doubt is not a pleasant condition, but certainty is absurd." Voltaire

        1. User avater
          Soultrain | Aug 12, 2006 05:33am | #10

          Are you sure about that?  The Codecheck book I have says that the vents only have to be 1/2 the size of the drain for the given fixture - with a minimum of 1 1/4"

          That would mean that since a toilet has a 3 inch drain, it would require a 1 1/2" vent...

          I do know that the total vent area needs to equal that of the building drain.

          1. hasbeen | Aug 12, 2006 07:37am | #12

            That's why I said you need to ask your inspector. Here a toilet has to have a 3" stack.+++++++++++++++++++++++++++++++++++++"Doubt is not a pleasant condition, but certainty is absurd." Voltaire

          2. plumbbill | Aug 12, 2006 07:46am | #13

            Table 7-5 of the UPC.

            Vent piping

            1.25"--- 1 fixture unit----- 45' maximum

            1.5"---- 8 FU's------ 60' max

            2"---- 24 FU's-------120'---- max

            2.5"----- 48 FU's----- 180'--- max

            Subsection note------1.5" vents are not permitted on 6 unit traps or water closets."can you cross your legs were short a nail" Pontius Pilate

          3. User avater
            BillHartmann | Aug 12, 2006 03:35pm | #14

            Here is part of the UBC table (you need to buy the book for the full one which is just what you posted).But is also ahs IRC (and I assume IPC is the same) in foot notes.IRC - vent >= 1/2 required drain diameter
            Vents > 40ft increase one pipe size.UPC increse vent one pipe size if horizontal exceeds 1/2 vertical lenght.This last one could easily be needed in a house with a long attic run to tie to a common vent.

      2. DanH | Aug 12, 2006 04:27am | #7

        The pipe sizes you state may not be correct, but you definitely can join them into a single vent before going through the roof.  The devil is in the details.
        If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

      3. plumbbill | Aug 12, 2006 05:00am | #8

        In most jurisdictions your vent must equal your building drain.

        Other than that you can run as many seperate drains as you want & run them a million miles if you want.

        Venting is ALMOST the same, but you're limited on distance & only 1/3 of the max can be horizontal. If you  oversize your vents then disregard the last statement."can you cross your legs were short a nail" Pontius Pilate

        1. brownbagg | Aug 12, 2006 05:05am | #9

          just put all your vents on the back side of the house, front views look bad.

  3. cat | Aug 12, 2006 06:39am | #11

    our inspector approved only one 2" vent through roof for new construction for three toilets (2 are stacked into same dwv line), 3 vanities, 2 showers, one washer BUT we also have three Studer vents (one way valves at the top of a 2" interior stack) as well. reason - we are using SIPS and minimal roof pentrations was critical to maintain efficiency. see if your inspector will allow these as well.

  4. Piffin | Aug 12, 2006 05:42pm | #15

    i'm not a plumber, but I have only roofed two or three houses in thirty some years that had only one stack

     

     

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    1. brownbagg | Aug 12, 2006 06:10pm | #16

      mine only has two, one for exhaust fans and one for sewer.

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