Island style vent for bathroom sink vent?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rvportland, Nov 11, 2006.

  1. rvportland

    rvportland New Member

    Messages:
    5
    Hi all,

    We are remodeling our upstairs bathroom, and our sink is moving to a different wall, away from the main stack and vent (old sink was jammed into a 20 inch space).

    Our problem is that the wall where the new sink drain is going in to is an interrior wall with a 2 1/8" ceiling joist running parallel right across the top of it, and it's in a very tight spot next to an old chimney and not really accessible to run the vent vertical and up through the roof.

    Would there be any problem with using an island style vent and running it under the floor, across the room to the other wall and back up to tap into the old stack?

    Any thoughts or advice are greatly appreciated.

    Thank you for looking,

    Robert
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    You only have to get the vent about 6" above the flood rim then you can go to your stack. It doesn't have to go directly up through the roof from there. When you attatch to the stack it must be the vent portion of the stack, there can't be any drains entering the stack above that point.
    Last edited: Nov 11, 2006
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vent

    As long as it is done properly, there is no problem using the island vent configuration. Some inspectors may question it, just because it is an unusual way to solve the problem, but I do it frequently when the sink is "boxed" in by posts and window headers.
  4. rvportland

    rvportland New Member

    Messages:
    5
    Wow, thank you for the speedy response!

    The vent would go up the wall behind the sink at least a foot above the flood rim, u-turn (island vent style), then back down under the floor, across the room, and back up the opposite wall to tie into the vent stack where the original sink did, (that tie in is also above the flood rim of the sink, although I am not sure it would really make a difference).

    On paper it looked like everything should be ok, because if the drain were to clog, there would be no way anything could drain through the vent, a clog would back up the sink first. But I wanted to ask an expert before I tackled moving it and I was affraid of what the city would say when they saw it. I was not sure they would be ok with the vent going up and then down again before heading over to the main vent, citing that gases always "rise".

    I just hope my inspector has nothing against creative plumbing =)

    Thanks again.

    Robert
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vent

    Your description leaves out one thing. There also has to be a "foot drain" before the vent goes up again so any condensate will drain out.
  6. rvportland

    rvportland New Member

    Messages:
    5
    I knew I was missing something!

    Would it be alright to tie the sink vent in with the tub vent? Both drains are 1 1/4 out of the fixtures, and the vent would be 1 1/2? If there is no problem in that, then I can tie into the old stack and not have to redo everything.

    http://i15.photobucket.com/albums/a355/irie23/RoughVentDiag.jpg

    Thank you for your advice on this. I was looking at having to take off work to go to the home-owner planning open hours (very limitted hours) to get help on this.

    Robert
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vent

    If you were to do it exactly as you show it, then that riser from the tub drain to the vent would not be accessible with a snake if it were to become plugged. You have to have "cleanouts" at points where the a snake could clear any obstructions.
  8. rvportland

    rvportland New Member

    Messages:
    5
    Vent riser cleanout

    Thank you for the response, hj.

    Hopefully this will be my last follow up question - You answer so many questions on these boards, I hate to keep bothering you.

    Is there any problem with plumbing like the diagram shows, if it had a cleanout added in the vent next to the riser you mentioned, if it were a foot away from a recessed light remodel can in the ceiling below, so that it would be accessible?

    I would love to just tear out all the old plumbing and start over, but I just do not have the budget to do it all at once, so I'm tackling it a little at a time. Although this 120 year old house really needs it, there are so many code violations down in the basement that passed inspection when we bought it 10 years ago, due to a grandfather clause, *sigh*.

    Once again, I appreciate all of your help.

    Robert
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vent

    What is needed, what is possible, and what will fit into your building may all be different. Tie the vent into the side of that short riser, then put a cleanout in the vent at the sink.
  10. rvportland

    rvportland New Member

    Messages:
    5
    The space should easily allow for that, so I will do it that way.

    Thank you for all the advice and the speedy replies!

    Robert.
  11. solsacre

    solsacre Plumber

    Messages:
    70
    Location:
    Arkansas
    That's a good picture, but if this will pass an inspection in... let's say Portland Oregon, and most other states, The Vent from the Tub and The Vent from the sink HAVE to tie into each other at least six inches above the flood level rim of the highest fixture... but every state is different. In Arkansas you simply send a 3 inch pipe through the floor with a cap on top and maybe a foot vent... (can't seem to get along with this new code book for proper answers) If this is in Oregon for example you will also need a clean-out on the vent going up the far wall. If you are on a budget, or simply happy to tackle new problems, I would contact a local plumber who knows your codes, buy him (or her) a beer and pay for an hour of his time to design it for you. It's cheaper than having the inspector tell you to tear it out and start new. good luck

    dances-with-pumps
    Last edited by a moderator: Apr 27, 2010
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