Bathroom DWV review

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by groggu, Aug 17, 2009.

  1. groggu

    groggu New Member

    Messages:
    4
    Location:
    2006 Michigan Plumbing Code
    Hi,
    I've been lurking on this forum for a while, trying to build my know-how so I can tackle the needed bathroom remodels in our 1870's farmhouse. The plumbing here is all afterthought (the original outhouse is still outback ;-) and has been put in by various farmers though the ages. When I took down the plaster in the lower bath, I found newspapers from 1949 - so I think it's been a while since this bathroom was updated.

    There are only 2 bathrooms in the house, one over the other. I'm remodeling the lower bathroom first and will get to the upper one next year. I don't want to have to rip the walls out of the lower bath after I finish it, so I'm planning the layout of the upper bath and roughing in DWV for the new toilet location, even though it won't be used yet.

    From what I've read in local codes and on this forum, I've been able to draw up my plan for the DWV (see below)
    [​IMG]

    The big change upstairs is that the toilet is moving and while I might be able to coax the waste line over to the new position, I'd rather just replumb it in it's proper location.

    The part of the layout that I'm having the most trouble understanding is the venting. Currently, both toilets are vented using the main stack - OK then, but not now. Let me know if you see any problems with this design. I know that the current connection for the upstairs toilet could be a problem because the vent runs horizontal for about 3 feet there. I'll be connecting so the vent goes up from where the toilet line joins the stack, but I'm not sure what fittings there are to make this work.

    Thanks for comments,

    Greg
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    Last edited: May 24, 2010
  3. groggu

    groggu New Member

    Messages:
    4
    Location:
    2006 Michigan Plumbing Code
    According to the township, we use the 2006 Michigan Plumbing Code which is based on the 2006 International Plumbing Code.

    Thanks,

    Greg
  4. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    Obviously it's a basic routing schematic that you have, it leaves a lot open to whether proper fittings used and elevations maintained. The biggest issue I see is where you're tying the second floor vents into your main waste/vent stack. That connection needs to happen about 42" above the second floor. You could tie these together on the first floor and take a single vent up but that will depend on structure. You'll need a vent in between the tub and current toilet (if they happen at the same time, else you'll need a vent for the tub anyway).

    Attached Files:

  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    Dwv

    Unless you can actually see your piping and drew it the way it is installed, you have made some assumptions which are probably incorrect. Tying the vents into the main stack below the upper toilet was NEVER correct, so either they do NOT connect there, or someone added the upper toilet without correcting the downstairs piping. As for the piping, a schematic is a concept, but the actual piping could be completely different depending on structural interference and other considerations.
  6. groggu

    groggu New Member

    Messages:
    4
    Location:
    2006 Michigan Plumbing Code
    Thanks for all the helpful input. Sorry I don't have a better means of drawing the layout - my hand drawn stuff would be even worse, so I appreciate your being able to see beyond that limitation. I know this is just a "logical" layout of the DWV. Just looking for suggestions to get it close to correct before going to the inspector.

    @FloridaOrange Thanks - 2 Q's
    1) So the main stack can't serve as the vent for the upper bath/wc group? That's OK, I can vent it, I just thought it was close enough to the main stack to use that as the vent.

    2) The upper bath vents "connection needs to happen about 42" above the second floor". I thought they just had to be above the ceiling. Is 42" code or standard practice? Just need to know because there's not a lot of room in the attic.

    @hg In my drawing (the first one) the vents for the lower bath are tied into the stack above the second floor toilet and are marked as dry vents. Currently in the house, the fixtures on both floors just use the stack for venting, so that's one of the things I'm trying to fix.

    Thanks all,

    Greg
  7. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    1. Stack vented fixtures need to tie individually to the stack.
    2. Horizontal vents in most cases need to run min. 6" above the flood rim of the highest fixtures, this is usually 42"
  8. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Nomination: Most confusing thread of the week :D

    The main stack, the one that runs down to the building drain. You can tie other vents into it, 6" above the flood level of the highest fixture served.

    Individual vents need to rise vertical to a point 6" above the flood level of the highest fixture served before they can be run horizontally.
  9. groggu

    groggu New Member

    Messages:
    4
    Location:
    2006 Michigan Plumbing Code
    I started out saying that I was not clear on venting :rolleyes:... now I think I'm starting to get it.

    In English - "All of the vents from the upper and lower baths need to individually enter the stack 6" above the waterline highest fixture on the second floor."

    I misread FloridaOrange's drawing and thought he was suggesting to tie into the stack below the 2nd floor toilet, which was confusing. I see now that he means to go up to the 2nd floor before entering the stack.

    I'm going to start over and see if I can get the bathroom groups to work together a little more cleanly.

    Thanks
  10. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    not quite, they can all tie into a header that ties into the stack also. It all depends on what is the most advantageous.
  11. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    [​IMG]
    A typical two story setup with vents tied back together at 6" above the flood level.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    vents

    You may be making this more complicated than necessary. The fixtures CAN use the main vent if the connect to it directly. Every fixture needs a vent, but not every one needs its OWN vent, the vents can be shared.
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