Distance from fixture to roof vent stack layout review (not distance from p-trap)

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by kmuddzy, Nov 30, 2011.

  1. kmuddzy

    kmuddzy New Member

    Messages:
    41
    Location:
    New Jersey
    Hi. New DIYer here. I wanted to know if there is a maximum distance for a fixture (kitchen sink) to the roof vent stack penetration? The diagram might explain it better. You can see the kitchen sink is on 1st floor and is about 26' horizontally from the 3" vertical soil stack that will run out the roof. BTW, this will be all new plumbing for an addition/remodel I am doing to my house. The only existing plumbing is the 3" septic line running to the septic tank.

    Also, any other comments on the layout? Last, I live in New Jersey so not sure if you need to know that.

    Thanks a LOT!

    Plumbing Vent Stack Layout.jpg
    Last edited: Nov 30, 2011
  2. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,225
    Location:
    Maine
    there actually is a maximum distance but it is determined by distance and pipe size. However you are nowhere near that distance.
  3. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    All of your fixture drains should be 2", except the tub, which can be 1.5 or 2".
    The combined drainage of the washer, shower, and lav are too great for a 2" horizontal drain.

    Depending on the layout, the shower could be wet vented through the lav but the laundry would get it's own branch drain.

    Without seeing it, I would think that running the kitchen vent straight up would be much easier. If it must be that way, it should have an extra cleanout on the 2nd floor.
  4. kmuddzy

    kmuddzy New Member

    Messages:
    41
    Location:
    New Jersey
    Thanks! I can change the washer, shower and dbl vanity drain to 3" and the fixture drains to 2". And you are right that running the kitchen vent straight up would be easier but there is no 2nd floor above it and the deck is on the outside of the kitchen window over the sink. This means the vent at the roof would only be about 12' - 14' above the deck surface (I can't run it near the peak) and I was afraid the wind might carry some of the smell down to the deck. Is that a concern?
  5. bluebinky

    bluebinky Member

    Messages:
    405
    Location:
    Santa Clara, CA
    I'd run 3"" horizontal to the kitchen with a cleanout at the end, if possible.
  6. kmuddzy

    kmuddzy New Member

    Messages:
    41
    Location:
    New Jersey
    Thanks for your reply. The clean out is a great idea. I can increase the pipe to 3" but if the only fixture drain on that run is 2" then why increase it to 3"? I have the room, I'm just curious why one would spend the extra $ for the additional size & fittings?
  7. bluebinky

    bluebinky Member

    Messages:
    405
    Location:
    Santa Clara, CA
    I'm not a pro, so do question what I say... I'm just saying what I would do (which can be overkill at times), not necessarily what you should do.

    My thinking is ease of cleaning out the main drain if it ever clogs -- a nice straight shot. Are you going to have a 3" 2-way cleanout outside which will allow you to fish upstream?

    Curious to know what hj or Tom say...
  8. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    I think you may run into problems running a long horizontal drain like that between the 1st & 2nd floors without cutting structural joists, not to mention maintaining enough pitch.
  9. kmuddzy

    kmuddzy New Member

    Messages:
    41
    Location:
    New Jersey
    Answering the cleanout question: I do not have a cleanout outside but there is one in the 3" existing line right before it leaves the basement and heads to the septic tank.

    Regarding the horizontal run: Normally I would've had issues running long horizontal runs like I'm showing but the way the addition was designed the 2nd story floor floats over the existing ceiling joists. This allows me to run the plumbing in between existing ceiling joists and new 2nd story floor joists plus the 2nd story floor joists run parallel to that long, horizontal direction giving me at least 16" of space to play with slope.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    quote; I'd run 3"" horizontal to the kitchen with a cleanout at the end, if possible

    possibly the WORST idea in a long time. The 2" is adequate and will be "self scouring". A 3" line will accumulate debris FASTER and be hard to unplug. The washer drain CANNOT be 1 1/2", but 2" is adequate for the same reason. Rgardless of what size drain line you install, and this applies to ALL situations, you MUST have a "full size" cleanout in the line, preferably at the upstream end.
    Last edited: Dec 1, 2011
  11. kmuddzy

    kmuddzy New Member

    Messages:
    41
    Location:
    New Jersey
    Thanks, HJ. 10-4 on 2" line. Is it OK to start with 1.5" pipe for the vents and increase it to 2" vent lines as I have shown?

    Regarding the "full size" cleanout in the line - does that apply to the 2nd floor drains too or just in the basement?

    Different questions: Does a soil stack vent have to be 3" or can it be reduced to 2" for the pipe above the fixture most upstream? Can I run the main soil stack vent pipe in an exterior wall and then angle it in the attic to keep it away from the front of the house as it pops through the roof or does a soil stack need to run plumb above the most upstream fixture?
    Last edited: Dec 1, 2011
  12. bluebinky

    bluebinky Member

    Messages:
    405
    Location:
    Santa Clara, CA
    Thanks hj!
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