Please help me plan the DWV for my bathroom remodel... toilet venting etc

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by coalminecanary, Aug 22, 2010.

  1. coalminecanary

    coalminecanary New Member

    Aug 22, 2010
    Hi all, First of all I have been a long time lurker and have appreciated many past threads so thanks to everyone who helps out on these forums!

    I am remodeling and need some advice. I will get right into it with the before/after.

    I have removed the vanity from my 2 piece and have replaced it with a shower stall.
    I wil linstall a small (9" deep) sink under the window resulting in a compact 3 piece bath.

    The toilet drains slowly ever since we put a low flow in last year. I figured it was due to venting, but in addition the 3" toilet line makes a 12 foot run at a very very slight slope - then it makes a 6 foot run which is virtually level. My understanding is I should be able to measure an inch of slope along the length of my four foot level and it is nowhere near that.

    So I plan to fix the slope of the toilet run as part of this remodel.

    The sink used to vent up into the ceiling where it turned horizontal to run to the main stack vent (separate from the waste stack). Seems good. The sink drined down and then a 6 foot run where it tied into the toilet line.

    Here is a crude drawing of before and after (top view)

    Here is where the old sink drain tied into the toilet. I suppose that it doubled as a wet vent for the toilet but I have no idea if that is functional (and probably not code-legal).
    IMG_2786 (Medium).jpg
    IMG_2785 (Medium).jpg

    I have a couple of questions:

    1. Toilet elbow: can I use a tighter elbow directly under the flange in order to get a bit more headroom to have better slope for the 12' run? How tight can I go?

    2. Toilet vent: I have no immediate vertical access for a toilet vent - Can I use the old sink drain line as a vent instead? i.e. drain the sink to the stack separately and use the joist drillings for the old sink drain to run a vent for the toilet all the way to the wall that will be behind the shower? such a vent would run 7 feet horizontal before turning up

    3. should I run a dedicated line from the shower to the stack (for drain - i plan to vent into ceiling for shower just as the sink used to be)? or should i tie the shower drain into the toilet drain the way the sink used to be? advantages of the latter are: a) don't have to put another wye into the stack. b)putting more fluid down the toilet's 12' run to help carry the solids away - for when the low flow flush simply doesn't put enough water through

    4. can I run an island style sink vent in the exterior wall directly behind the new small sink? i.e. an upside-down U that goes above sink level, then back into floor where i can tie into the vent behind the shower?

    lots of questions I know, thanks for your patience!
  2. coalminecanary

    coalminecanary New Member

    Aug 22, 2010
    I am learning sketchup and will post images of my plan soon - it should make everything much more clear then!
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