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  1. #1
    Richard Roshak's Avatar
    Richard Roshak Guest

    Default Vent pipe in attic

    The owner ran this plumbing vent up, over and down, so that he could install pull down stairs. I don't think this is a problem, however I thought I would ask to be sure.

    Rich

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  2. #2
    Jon Randolph's Avatar
    Jon Randolph Guest

    Default Re: Vent pipe in attic

    By up, over and down I assume that you mean he created an upside down u (or an n) with the vent pipes. If so, this is wrong. It will trap rain water and condensate in the section that goes up and through the roof.


    BTW....

    I always write up those cheap pull down stairs as low quality and caution the client about relying on them to enter/exit the attic safely. I also list them as a breach of the fire separation between the home and garage if installed in the garage, unless provisions have been made to resist fire.


  3. #3
    Richard Roshak's Avatar
    Richard Roshak Guest

    Default Re: Vent pipe in attic

    It does not go through the roof and it terminates into a main vent.
    Rich


  4. #4
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    Default Re: Vent pipe in attic

    Vent is still wrong, needs to slope and not trap condensation.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  5. #5
    Join Date
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    Default Re: Vent pipe in attic

    A vent needs to "vent".

    That's a large trap, that is not going to "vent" (at least not properly).

    He would have been better off (and it would have been easier and cheaper - less pipe) to 'go around'. Sloping uphill as he went 'around'.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6

    Default Re: Vent pipe in attic

    Like everyone else has said-- wrong. Everything must slope back toward the sewer line.


  7. #7
    Richard Roshak's Avatar
    Richard Roshak Guest

    Default Re: Vent pipe in attic

    Lost my head today. 1/4" per foot back to the main drain/vent.
    Rich


  8. #8
    Jon Randolph's Avatar
    Jon Randolph Guest

    Default Re: Vent pipe in attic

    Quote Originally Posted by Richard Roshak View Post
    Lost my head today. 1/4" per foot back to the main drain/vent.
    Rich
    That is the minimum for waste piping but as long as there is some slope in the vent piping, I wouldn't get excited. You don't have to worry about solids settling out in the vent, unless it is a wet vent in which case it becomes waste piping.


  9. #9
    Tony Watson's Avatar
    Tony Watson Guest

    Default Re: Vent pipe in attic

    If both Horizontal pipes are slopped in the direction that they would drain, then this configuration will work. The pipe size though is another issue. The configuration as shown looks like an "island vent", without a sink draining into it.


  10. #10
    Joshua Hardesty's Avatar
    Joshua Hardesty Guest

    Default Re: Vent pipe in attic

    Tony: I don't believe the photo shows two vents flowing away from eachother that tie in above where we can see adn then shoot out the roof. We're looking at what used to be one long horizontal vent running near the floor, that the homeowner jogged up out of his way so they could put in an access to the attic, so both horizontal pipes are sloped the same way.


  11. #11
    Tony Watson's Avatar
    Tony Watson Guest

    Default Re: Vent pipe in attic

    Quote Originally Posted by Richard Roshak View Post
    It does not go through the roof and it terminates into a main vent.
    Rich
    If one side ties into a vent TEE and the other side is the upper section of a common or individual vent then both sides have to drain to a stack, with the right grade of course.


  12. #12
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    Default Re: Vent pipe in attic

    Quote Originally Posted by Tony Watson View Post
    If The configuration as shown looks like an "island vent", without a sink draining into it.
    Tony,

    Think of it as a "high loop" instead of an "island vent".

    The island vent is tied back down to the drain, creating a vent path.

    That is a high loop, not tied back down to anything, creating a trap (inverted trap, which traps air).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  13. #13
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    Default Re: Vent pipe in attic

    Not to change the subject... Were the trusses design for attic storage? If he did this as an after thought, they're most likely not. Looks like a lot of "stuff" up there, along with the extra plywood load. Attics with limited storage are required to have live load of 20 psf applied to the bottom cord. Something you may want to note.

    Last edited by Door Guy; 12-07-2009 at 06:18 PM. Reason: spelling
    Randy Gordon, construction
    Michigan Building Inspector/Plan Reviewer

  14. #14
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    Default Re: Vent pipe in attic

    Quote Originally Posted by Door Guy View Post
    Not to change the subject... Were the trusses design for attic storage? If he did this as an after thought, they're most likely not. Looks like a lot of "stuff" up there, along with the extra plywood load. Attics with limited storage are required to have live load of 20 psf applied to the bottom cord. Something you may want to note.

    And, if read notes b and g, you would also have noted:
    - b. Attics without storage are those where the maximum clear height between joist and rafter is less than 42 inches, or where there are not two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high by 2 feet wide, or greater, located within the plane of the truss. For attics without storage, this live load need not be assumed to act concurrently with any other live load requirements.
    - g. For attics with limited storage and constructed with trusses, this live load need be applied only to those portions of the bottom chord where there are two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high or greater by 2 feet wide or greater, located within the plane of the truss. The rectangle shall fit between the top of the bottom chord and the bottom of any other truss member, provided that each of the following criteria is met:
    - - 1. The attic area is accessible by a pull-down stairway or framed opening in accordance with Section R807.1; and
    - - 2. The truss has a bottom chord pitch less than 2:12.

    - R502.3.1 Sleeping areas and attic joists. Table R502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section R311.5 provided that the design live load does not exceed 30 psf (1.44 kPa) and the design dead load does not exceed 20 psf (0.96 kPa). The allowable span of ceiling joists that support attics used for limited storage or no storage shall be determined in accordance with Section R802.4.
    - R502.3.2 Other floor joists. Table R502.3.1(2) shall be used to determine the maximum allowable span of floor joists that support all other areas of the building, other than sleeping rooms and attics, provided that the design live load does not exceed 40 psf (1.92 kPa) and the design dead load does not exceed 20 psf (0.96 kPa).

    The trusses in the photo, then, would most likely have been designed for a live load of either 30 psf or 40 psf ... because they are definitely not designed for "limited storage".


    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  15. #15
    Join Date
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    Default Re: Vent pipe in attic

    Quote Originally Posted by Door Guy View Post
    Attics with limited storage are required to have live load of 20 psf applied to the bottom cord. Something you may want to note.
    Really? You have to apply the live load, not just design for it?

    "Baseball is like church. Many attend but few understand." Leo Durocher
    Bruce Breedlove
    www.avaloninspection.com

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