Asking for some line size help...

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by painterjoe, May 2, 2014.

  1. painterjoe

    painterjoe New Member

    Messages:
    2
    Location:
    WA
    I am trying to plan the finishing of my two story addition. I live in Washington state so I am assuming this falls under the guidelines of the UPC. What I want to do is have a laundry room w/shower, sink and john on the first floor. Opposite this, there will be a kitchen with a sink. (opposite meaning on the other side of a 2X6 wall). On the second floor, I would like to have a half bath and opposite this, would be a full bath with walk-in shower. Maybe throw in a claw foot tub too. Again, opposite being on the other side of a 2X6 wall. The downstairs kitchen would be below the upstairs full bath and the downstairs laundry bath area would be below the upstairs half bath. I am trying to have a single large vent exiting the roof and also have all the drains tie into this single main stack and drain.
    So I have a couple of questions to ask. ( I don't know how many total fixture 'units' this equates to)
    I don't know how feasible this is, is it? Could I get away with 3" drain line or is 4" going to be what I need? Would it be better to try and vent the upper full bath separately? I am trying to stay away from exterior wall piping, but don't know if that applies to dmv stuff for codes/freezing/nail issues. If I can use a smaller vent pipe for all of this, where does the transition(s) take place? Anyhow, that is where I am at. When I called the county, all I got was get your permit and we will tell you what to do. That's nice, but I want to know what to do before I have to actually do it and am tied down with meeting permit requirements on their schedule. (I like to plan ahead for costs and etc.)
    Any help would be greatly appreciated.
    Thank you
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,267
    Location:
    Cave Creek, Arizona
    What you are asking is WAY beyond what anyone should attempt to answer by an E-mail or Internet post. I am surprised the county even said that. Usually they say, "bring us a COMPLETE set of drawings showing what you intend to do and we will reject them until you get it right, because we are NOT in the design business,"
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,312
    Location:
    Maine
    You're in Washington. Give Terry a call, he can take care of the whole job for you.
  4. MaxWarp

    MaxWarp New Member

    Messages:
    6
    Location:
    IL
    You're going to need a 4" line. You have too many fixtures going down one line to be less than that. You're also going to need at least a 3" vent to the roof for all of this. You'll be able to tie to together for the vent but not reduce it. I'm also surprised that the county would offer any help trying to design anything.
  5. painterjoe

    painterjoe New Member

    Messages:
    2
    Location:
    WA
    4 inch iit is...

    Thanks everybody for the help. Since I have to have at least a 3 inch vent, then I will plan on using 4 inch throughout, just to be safe.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,267
    Location:
    Cave Creek, Arizona
    It appears that you only have three toilets, and if so, you onlY NEED a 3" pipe and it would be better than using 4". The size of the vent is usually predicated upon the size of your main line, therefore, if you have a 4" main, the total area, not diameters, of the vent through the roof would have to equal the area of a 4" pipe, meaning either a 4" vent or a 3" vent PLUS a couple of smaller ones.
    Last edited: May 3, 2014
  7. MaxWarp

    MaxWarp New Member

    Messages:
    6
    Location:
    IL
    HJ, I'm not questioning you as you're a licensed professional but wouldn't 3 toilets, plus sinks, laundry, etc overload a 3" possibly? If everybody flushes at once while the laundry is draining wouldn't that be a little much? Just trying to be more educated as a DIYer. Thanks!
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,422
    Location:
    Bothell, Washington
    With UPC, there is no need for 4" until the forth toilet is added on the horizontal.
    You could run that entire stack with a 2" vent if you also have other vents in the home to make up the composite area. For a three bath home, that is normally
    3" or two 2" and one 1.5"
    For a four bath home,
    4" or four 2" vents

    A pretty typical two bath setup with 2" vent.

    [​IMG]
Similar Threads: Asking line
Forum Title Date
Plumbing Forum, Professional & DIY Advice Plumbing permit drawing -- asking for any feedback Jul 3, 2009
Plumbing Forum, Professional & DIY Advice Another thread asking advice on disposal setup Feb 9, 2007
Plumbing Forum, Professional & DIY Advice Am I asking for trouble with this fix? Apr 16, 2005
Plumbing Forum, Professional & DIY Advice Can I reuse the same Copper flare line connected to a gas valve Thursday at 11:08 AM
Plumbing Forum, Professional & DIY Advice Roughing in PE gas line before landscaping Dec 13, 2014

Share This Page