Is it OK to Vent a Toilet, Shower & Bath Sink into the Attic - at the Roof Ridge Vent?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by RogerPDX, Feb 23, 2016.

  1. RogerPDX

    RogerPDX Member

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    I am replacing my comp roof with a metal roof and would like to eliminate all holes in my new roof, if possible.

    Is it legal (or does it at least work just fine) to cut my 3 vent pipes that are in my attic and attach angles and pipe angeling all 3 vents up to the underside of my roof ridge cap? Does this work ok?

    or...

    Can I cut the vent pipes in my attic above the top plate that they presently come through and attach Studor Vents to the top of each cut vent pipe? Is this legal? Would I get ANY smells with this method?

    Thanks for your answers.
     
  2. Terry

    Terry Administrator Staff Member

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    You need to extend at least one vent through the roof.
    As to the Studor vents, you are always better off going through the roof long term. The mechanical vents will need replacing at some point. Will anyone even know where they are to replace them?

     
    Last edited: Feb 24, 2016
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  4. RogerPDX

    RogerPDX Member

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    How long do the Studor vents last?

    Why one vent through the roof & 2 to the ridge cap?
     
  5. hj

    hj Moderator & Master Plumber Staff Member

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    NONE at the ridge cap. One vent through the roof and the others connected to it in the attic. Studor vents can cause as many problems as they solve. The only time the do not is when they ARE broken.
     
  6. RogerPDX

    RogerPDX Member

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    If that is code, ok - but would it work just the same to bring the vent(s) internally up to the underside of the ridge cap? What would be the drawback in doing it this way?
     
  7. DaveHo

    DaveHo Member

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    Uh, sewer gasses in your attic?
     
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Sewer gas can not only be noxious, it can be explosive, plus, the moisture in it could condense, creating mold and rot. It needs to vent high enough above the roof so that it is dissipated reliably. Depending on the wind, trying to exhaust it at the ridge vent might just blow it back into the attic. If you want to minimize the roof penetrations, it might be allowed to go out the end wall, but it would still need to extend high enough, and most people much prefer it going through the roof verses the vertical sidewall. If you're going to combine multiple vent stacks in the attic, the remaining one that goes through the roof would need to be larger and keep in mind that the vents MUST have negative slope on them to allow condensation and precipitation to flow down to the sewer.
     
  9. cacher_chick

    cacher_chick Test, Don't Guess!

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    Here is what our plumbing code has to say, most others are similar-

    VENT TERMINALS. All vents and vent systems shall terminate in the open air in accordance with this subsection.
    (a) Extension above roofs. Extensions of vents through a roofshall terminate at least 8" above the roof. Where the roof is to be used for any purpose other than weather protection, the vents shall extend at least 7 feet above the roof.
    (b) Waterproof flashings. The penetration of a roof system bya vent shall be made watertight with an approved flashing.
    (c) Prohibited uses. Vent terminals shall not be used as flagpoles, support for antennas or other similar purposes.
    (d) Location of vent terminals. 1. A vent shall not terminate under the overhang of a building. 2. All vent terminals shall be located:
    a. At least 10 feet from an air intake;
    b. At least 5 feet from a power exhaust vent;
    c. At least 10 feet horizontally from or 2 feet above roofscuttles, doors and openable windows; and
    d. At least 5 feet from or 2 inches above parapet walls.
    3. Where a structure has an earth covered roof extending from surrounding grade, the vent extension shall run at least 7 feet above grade and terminate with an approved vent cap. The portion of vent pipe outside the structure shall be without joints, except one fitting may be installed where the pipe leaves the top or side of the structure.(e) Extension through wall. Where specifically approved by the department, a vent may terminate through an exterior wall. Such a vent shall terminate at least 10 feet horizontally from any lot line and shall terminate downward. The vent shall be screened and shall comply with par. (d).
    (f) Extensions outside buildings. Drain or vent pipe extensions shall not be located or placed on the outside of an exterior wall of any new building, but shall be located inside the building.
    (g) Frost closure. For protection against frost closure, eachvent terminal shall be at least 2" in diameter. Where it is necessary to increase the diameter of the vent, the change in diameter shall be made at least 6" inside the building.
     
  10. RogerPDX

    RogerPDX Member

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    I understand the necessity now. Thanks to all who answered. I don't however understand what you mean by 'negative slope'. Can you please explain this?
     
  11. Terry

    Terry Administrator Staff Member

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    The vents drain downward to the drains. Negative
    Or you could say that the horizontal vents grade slightly upward to the sky. Positive
     
  12. RogerPDX

    RogerPDX Member

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    So if I leave my toilet vent through the roof (it has a sink vent venting into it - I think horizontally),
    and angle my shower vent over to it in the attic (creating only one hole in the roof) what degree of angle should the shower vent pipe be?
     
  13. hj

    hj Moderator & Master Plumber Staff Member

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    Install it EXACTLY the way you would do a drain line and it will have the correct slope in the right direction. Do not worry about "negative" or "positive" slope because that will just confuse you.
     
  14. DaveHo

    DaveHo Member

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    I'm far from being a professional, but the questions you are asking are a clear indication you should pay a qualified plumber to do this work.
     
    MASTERPLUMB777 likes this.
  15. standardairconditioner

    standardairconditioner HVAC'ker

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    A tremendous amount of humidity and moisture will dew up into any vent that is capped with an AAV, so you definitely don't want any collected water that may stagnate in your vent pipes. You want everything correctly sloped so this collected dew can still drain.

    It is strongly recommended you seek a licensed professional to do this work, and might as well put a hole into your roof, where you will benefit from a vent that will both suck in air and release moisture.

    The AAV will fail eventually, and you want to hide yours in the attic. I usually install AAV's to be found under the sink, where the DIY homeowner can just unscrew it and replace a new one on their own.

    A hole in a roof doesn't "weaken" the roof as you may be afraid of. When a roof flashing is installed and sealed correctly, your first point of failure will be the rest of the shingles on the roof, way before any rainwater is leaked through this hole.
     
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  16. RogerPDX

    RogerPDX Member

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    Does that mean to run the shower vent pipe horizontally over to the main vent from the toilet (that goes up through the roof) or run it at an angle 'down' to that main vent?

    I have a friend who is a retired plumber who never worries about water being angled downward into a drain - he tells me horizontal runs do just fine. Can that be correct?
     
  17. Terry

    Terry Administrator Staff Member

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    Horizontal is 1/4" per foot grade.
    Nothing is ever run flat.
     
  18. RogerPDX

    RogerPDX Member

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    So "drop" the vent from the shower over to the toilet vent 1/4" per foot? (Grade down over to the toilet vent?)
     
    Last edited: Feb 25, 2016
  19. cacher_chick

    cacher_chick Test, Don't Guess!

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    Your questions are specific enough that I would need to see the actual layout of the drains and vents to determine if it it correct.
     
  20. Storm rider

    Storm rider Slave to rentals

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    No, raise the vent from the shower over to the toilet vent, that goes through the roof, by 1/4" per foot.
     
  21. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Any horizontal run of a drain MUST have at LEAST 1/4" per foot down (negative) so that they can drain down.

    When combining things, there are some code restrictions on WHERE you can do this. FOr example, from a trap arm, you MUST go up at least 42" above the floor OR 6" above the flood plane of anything that is being vented in that group, whichever is higher before you can go horizontal. So, that might make a decision for you on which end of a run must move.
     
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